UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    Form 13F

                               Form 13F COVER PAGE

Report for the Calendar Year or Quarter Ended: June 30, 2008

Check here if Amendment [ ]; Amendment Number: __________
     This Amendment (Check only one): [ ] is a restatement.
                                      [ ] adds new holdings entries.

Institutional Investment Manager Filing this Report:

Name:    Alleghany Corporation
Address: 7 Times Square Tower, 17th Floor
         New York, NY 10036

Form 13F File Number: 28-1590

The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

Name:  Peter R. Sismondo
Title: Vice President
Phone: 212-752-1356

Signature, Place, and Date of Signing:


/s/ Peter R. Sismondo                     New York, NY         August 7, 2008
-------------------------------------   ----------------   ---------------------
             [Signature]                  [City, State]            [Date]

Report Type (Check only one):

[X]  13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
     are reported in this report.)

[ ]  13F NOTICE. (Check here if no holdings reported are in this report, and all
     holdings are reported by other reporting manager(s).)

[ ]  13F COMBINATION REPORT. (Check here if a portion of the holdings for this
     reporting manager are reported in this report and a portion are reported by
     other reporting manager(s).)



                              Form 13F SUMMARY PAGE

Report Summary:

Number of Other Included Managers:                 2
Form 13F Information Table Entry Total:           90
Form 13F Information Table Value Total:   $1,377,600
                                          (thousands)

List of Other Included Managers:

No.   Form 13F File Number   Name
---   --------------------   ----
2                            RSUI Indemnity Company
3                            Alleghany Insurance Holdings LLC



SECURITIES AND EXCHANGE COMMISSIONS FORM 13F INFORMATION
PREPARED FOR ALLEGHANY CORPORATION
AS OF 06/30/08



          COLUMN 1              COLUMN 2     COLUMN 3  COLUMN 4       COLUMN 5          COLUMN 6    COLUMN 7    COLUMN 8
---------------------------- -------------- --------- --------- ------------------- --------------- -------- --------------
                                                                                      INVESTMENT                 VOTING
                                                        MARKET                        DISCRETION                AUTHORITY
                                                        VALUE    SHRS OR   SH/ PUT/ SOLE SHRD OTHER          SOLE SHRD NONE
       NAME OF ISSUER        TITLE OF CLASS   CUSIP    (X 1000)  PRIN AMT  PRN CALL  (A)  (B)  (C)   MANAGER  (A)  (B)  (C)
---------------------------- -------------- --------- --------- ---------- --- ---- ---- ---- ----- -------- ---- ---- ----
                                                                                
NABORS INDUSTRIES LTD        SHS            G6359F103    41,599    845,000  SH            X             2      X
NABORS INDUSTRIES LTD        SHS            G6359F103     7,877    160,000  SH            X             3      X
WEATHERFORD INTERNATIONAL LT COM            G95089101     7,530    151,840  SH            X             2      X
WEATHERFORD INTERNATIONAL LT COM            G95089101     8,926    180,000  SH            X             3      X
AT&T INC                     COM            00206R102     1,347     40,000  SH                  X       3      X
AGILENT TECHNOLOGIES INC     COM            00846U101     1,088     30,600  SH                  X       3      X
ALEXANDER & BALDWIN INC      COM            014482103       911     20,000  SH                  X       3      X
AMERICAN EXPRESS CO          COM            025816109     1,386     36,800  SH                  X       3      X
AMERICAN INTL GROUP INC      COM            026874107       624     23,600  SH                  X       3      X
APPLERA CORP                 COM AP BIO GRP 038080103       670     20,000  SH                  X       3      X
APPLIED MATLS INC            COM            038222105       955     50,000  SH                  X       3      X
AUTODESK INC                 COM            052769106     1,014     30,000  SH                  X       3      X
AUTOMATIC DATA PROCESSING IN COM            053015103       838     20,000  SH                  X       3      X
BERKSHIRE HATHAWAY INC DEL   CL B           084670207     1,605        400  SH                  X       3      X
BOEING CO                    COM            097023105       986     15,000  SH                  X       3      X
BURLINGTON NORTHN SANTA FE C COM            12189T104   399,560  4,000,000  SH       X                  1      X
CAMECO CORP                  COM            13321L108     2,144     50,000  SH            X             2      X
CAMECO CORP                  COM            13321L108     1,072     25,000  SH            X             3      X
CATERPILLAR INC DEL          COM            149123101     1,846     25,000  SH                  X       3      X
CHESAPEAKE ENERGY CORP       COM            165167101     3,298     50,000  SH            X             2      X
CHESAPEAKE ENERGY CORP       COM            165167101    11,543    175,000  SH            X             3      X
CHEVRON CORP NEW             COM            166764100    31,226    315,000  SH            X             2      X
CHEVRON CORP NEW             COM            166764100    16,961    171,100  SH            X             3      X
CHICAGO BRIDGE & IRON CO N V NY REGISTRY SH 167250109    15,629    392,500  SH            X             2      X
CHICAGO BRIDGE & IRON CO N V NY REGISTRY SH 167250109     6,272    157,500  SH            X             3      X
CHUBB CORP                   COM            171232101     1,470     30,000  SH                  X       3      X
COCA COLA CO                 COM            191216100     1,310     25,200  SH                  X       3      X
COMCAST CORP NEW             CL A           20030N101       260     13,700  SH            X             3      X
CONOCOPHILLIPS               COM            20825C104    30,205    320,000  SH            X             2      X
CONOCOPHILLIPS               COM            20825C104    61,920    656,000  SH            X             3      X
COSTCO WHSL CORP NEW         COM            22160K105     2,104     30,000  SH                  X       3      X
DARWIN PROFESSIONAL UNDERWRI COM            237502109   288,630  9,371,096  SH            X             3      X
DEERE & CO                   COM            244199105     2,164     30,000  SH                  X       3      X
DEVON ENERGY CORP NEW        COM            25179M103    53,171    442,500  SH            X             2      X
DEVON ENERGY CORP NEW        COM            25179M103    16,822    140,000  SH            X             3      X
DISNEY WALT CO               COM DISNEY     254687106     1,404     45,000  SH                  X       3      X
DOMTAR CORP                  COM            257559104     2,376    436,000  SH            X             2      X
DOMTAR CORP                  COM            257559104       894    164,000  SH            X             3      X
DU PONT EI DE NEMOURS & CO   COM            263534109     1,287     30,000  SH                  X       3      X
EOG RES INC                  COM            26875P101     6,298     48,000  SH            X             2      X
EOG RES INC                  COM            26875P101     2,230     17,000  SH            X             3      X
EXXON MOBIL CORP             COM            30231G102     2,644     30,000  SH                  X       3      X
FPL GROUP INC                COM            302571104     9,575    146,000  SH            X             2      X
FPL GROUP INC                COM            302571104     3,541     54,000  SH            X             3      X
FEDEX CORP                   COM            31428X106     1,182     15,000  SH                  X       3      X
FIDELITY NATL FINANCIAL      CL A           31620R105     3,072    243,800  SH            X             2      X
FIDELITY NATL FINANCIAL      CL A           31620R105       630     50,000  SH            X             3      X
FLOTEK INDS INC DEL          COM            343389102     4,743    230,000  SH            X             2      X
FLOTEK INDS INC DEL          COM            343389102     3,093    150,000  SH            X             3      X
GENERAL ELECTRIC CO          COM            369604103    11,076    415,000  SH            X             2      X
GENERAL ELECTRIC CO          COM            369604103     6,472    242,500  SH                  X       3      X
GLOBAL INDS LTD              COM            379336100    15,689    875,000  SH            X             2      X
GLOBAL INDS LTD              COM            379336100     5,827    325,000  SH            X             3      X
HOME DEPOT INC               COM            437076102       468     20,000  SH                  X       3      X
INTEL CORP                   COM            458140100     1,504     70,000  SH                  X       3      X
INTERNATIONAL BUSINESS MACHS COM            459200101     1,482     12,500  SH                  X       3      X
INTL PAPER CO                COM            460146103    11,068    475,000  SH            X             2      X
INTL PAPER CO                COM            460146103     4,078    175,000  SH            X             3      X
INTUIT                       COM            461202103       551     20,000  SH                  X       3      X
ISHARES INC                  MSCI JAPAN     464286848       258     20,700  SH            X             3      X
JOHNSON AND JOHNSON          COM            478160104     1,383     21,500  SH                  X       3      X
KELLOGG                      COM            487836108       960     20,000  SH                  X       3      X
KEY ENERGY SVCS INC          COM            492914106     8,739    450,000  SH            X             2      X
KEY ENERGY SVCS INC          COM            492914106     3,884    200,000  SH            X             3      X
KRAFT FOODS INC              CL A           50075N104     8,413    295,700  SH            X             2      X



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SECURITIES AND EXCHANGE COMMISSIONS FORM 13F INFORMATION
PREPARED FOR ALLEGHANY CORPORATION
AS OF 06/30/08



          COLUMN 1              COLUMN 2     COLUMN 3  COLUMN 4       COLUMN 5          COLUMN 6    COLUMN 7    COLUMN 8
---------------------------- -------------- --------- --------- ------------------- --------------- -------- --------------
                                                                                      INVESTMENT                 VOTING
                                                        MARKET                        DISCRETION                AUTHORITY
                                                        VALUE    SHRS OR   SH/ PUT/ SOLE SHRD OTHER          SOLE SHRD NONE
       NAME OF ISSUER        TITLE OF CLASS   CUSIP    (X 1000)  PRIN AMT  PRN CALL  (A)  (B)  (C)   MANAGER  (A)  (B)  (C)
---------------------------- -------------- --------- --------- ---------- --- ---- ---- ---- ----- -------- ---- ---- ----
                                                                                
KRAFT FOODS INC              CL A           50075N104     2,134     75,000  SH            X             3      X
LAUDER ESTEE COS INC         CL A           518439104     1,161     25,000  SH                  X       3      X
LEGGETT & PLATT INC          COM            524660107    28,257  1,685,000  SH            X             2      X
LEGGETT & PLATT INC          COM            524660107    10,314    615,000  SH            X             3      X
LILLY ELI & CO               COM            532457108     1,385     30,000  SH                  X       3      X
LINCOLN NATIONAL CORP IND    COM            534187109       814     17,963  SH                  X       3      X
MANPOWER INC                 COM            56418H100       874     15,000  SH                  X       3      X
MARRIOTT INTL INC NEW        CL A           571903202       918     35,000  SH                  X       3      X
MCDERMOTT INTL INC           COM            580037109     5,261     85,000  SH            X             2      X
MCDERMOTT INTL INC           COM            580037109     2,475     40,000  SH            X             3      X
MEDTRONIC INC                COM            585055106     1,646     31,800  SH                  X       3      X
MICROSOFT CORP               COM            594918104     2,124     77,200  SH                  X       3      X
MILLIPORE CORP               COM            601073109     1,357     20,000  SH                  X       3      X
MOTOROLA INC                 COM            620076109        83     11,300  SH            X             3      X
NEWS CORP                    CL A           65248E104     1,053     70,000  SH                  X       3      X
NOBLE ENERGY INC             COM            655044105     3,017     30,000  SH                  X       3      X
NORDSTROM INC                COM            655664100       909     30,000  SH                  X       3      X
NOVARTIS AG                  SPONSORED ADR  66987V109     1,376     25,000  SH                  X       3      X
NUSTAR ENERGY LP             UNIT COM       67058H102     1,478     31,190  SH            X             2      X
NUSTAR ENERGY LP             UNIT COM       67058H102     1,592     33,600  SH            X             3      X
OLD REP INTL CORP            COM            680223104    16,576  1,400,000  SH            X             3      X
PHH CORP                     COM            693320202     2,184    142,300  SH                  X       3      X
PETROLEO BRASILEIRO SA PETRO SPONSORED ADR  71654V408    10,164    143,500  SH            X             2      X
PETROLEO BRASILEIRO SA PETRO SPONSORED ADR  71654V408     4,002     56,500  SH            X             3      X
PFIZER INC                   COM            717081103    11,792    675,000  SH            X             2      X
PFIZER INC                   COM            717081103     5,678    325,000  SH            X             3      X
PLAINS EXPL& PRODTN CO       COM            726505100     3,904     53,500  SH            X             2      X
PLAINS EXPL& PRODTN CO       COM            726505100     2,299     31,500  SH            X             3      X
PROCTER & GAMBLE CO          COM            742718109     1,879     30,900  SH                  X       3      X
SPDR TR                      UNIT SER 1     78462F103       307      2,400  SH            X             3      X
SCHLUMBERGER LTD             COM            806857108     2,686     25,000  SH                  X       3      X
SIGMA ALDRICH CORP           COM            826552101     1,616     30,000  SH                  X       3      X
SONY CORP                    ADR NEW        835699307     1,094     25,000  SH                  X       3      X
STATE STR CORP               COM            857477103       960     15,000  SH                  X       3      X
STATOILHYDRO ASA             SPONSORED ADR  85771P102     4,579    122,500  SH            X             2      X
STATOILHYDRO ASA             SPONSORED ADR  85771P102     1,589     42,500  SH            X             3      X
SYSCO CORP                   COM            871829107       825     30,000  SH                  X       3      X
TESORO CORP                  COM            881609101     8,402    425,000  SH            X             2      X
TEXAS INSTRS INC             COM            882508104       597     21,200  SH                  X       3      X
3M CO                        COM            88579Y101     1,531     22,000  SH                  X       3      X
TRICO MARINE SERVICES INC    COM NEW        896106200    10,835    297,500  SH            X             2      X
TRICO MARINE SERVICES INC    COM NEW        896106200     4,279    117,500  SH            X             3      X
VALERO ENERGY CORP NEW       COM            91913Y100    12,766    310,000  SH            X             2      X
VALERO ENERGY CORP NEW       COM            91913Y100     6,589    160,000  SH            X             3      X
WACHOVIA CORP 2ND NEW        COM            929903102       627     40,400  SH                  X       3      X
WAL MART STORES INC          COM            931142103     2,529     45,000  SH                  X       3      X
WASHINGTON POST CO           CL B           939640108       880      1,500  SH                  X       3      X
WELLS FARGO & CO NEW         COM            949746101       603     25,400  SH                  X       3      X
WEYERHAUSER CO               COM            962166104     1,023     20,000  SH                  X       3      X
WYETH                        COM            983024100     9,112    190,000  SH            X             2      X
WYETH                        COM            983024100     4,077     85,000  SH            X             3      X
XTO ENERGY INC               COM            98385X106     2,364     34,500  SH            X             2      X
XTO ENERGY INC               COM            98385X106     1,062     15,500  SH            X             3      X
ZENITH NATL INS CORP         COM            989390109    20,178    573,879  SH            X             3      X
GRAND TOTAL                                           1,377,600 31,857,568



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