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EXHIBIT 21
HCC INSURANCE HOLDINGS, INC.
SUBSIDIARIES
<Table>
<Caption>
STATE OR COUNTRY OF
NAME INCORPORATION
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1. 5308 Acquisition Co., LLC Delaware
2. American Contractors Indemnity Company California
3. ASU International, Inc. Massachusetts
4. ASU International Limited United Kingdom
5. Avemco Corporation Delaware
6. Avemco Insurance Company Maryland
7. Avemco Services, Inc. Maryland
8. Aviation & Marine Premium Acceptance Corporation Texas
9. Centris Insurance Company Indiana
10. Centris Underwriting Agencies, Inc. Indiana
11. Continental Underwriters Ltd. Louisiana
12. Covenant Claims Service, LLC Louisiana
13. Covenant Underwriters, Ltd. Louisiana
14. Dickson Manchester & Company, Limited United Kingdom
15. Eagles Aerobatic Flight Team, Inc. Wisconsin
16. Eastern Aviation & Marine Underwriters, Inc. Maryland
17. Euro Sports Underwriters Limited United Kingdom
18. Great American Industries, Inc. Louisiana
19. HCC Acquisition Sub, Inc. New York
20. HCC Acquisitions (U.K.) Ltd. United Kingdom
21. HCC Administrators, Inc. Illinois
22. HCC Aviation Insurance Group, Inc. Texas
23. HCC Aviation, LLC Delaware
24. HCC Aviation, Ltd. Texas
25. HCC Benefits Corporation Delaware
26. HCC Diversified Financial Products Limited United Kingdom
27. HCC Employee Benefits, Inc. Delaware
28. HCC Employer Services, Inc. Alabama
29. HCC Employer Services, Inc. Illinois
30. HCC Global Financial Products, LLC Delaware
31. HCC Global Financial Products of Alabama, LLC Alabama
32. HCC Global Financial Products of Texas, LLC Texas
33. HCC Global Financial Products, SL, Unipersonal, a Spanish Sociedad Limitada Spain
34. HCC Intermediate Holdings, Inc. Delaware
35. HCC Life Insurance Company Indiana
36. HCC Properties, LLC Delaware
37. HCC Reinsurance Company Limited Bermuda
38. HCC Risk Management Corporation Texas
39. HCC Risk Management, Inc. Indiana
40. HCC Service Company, Ltd. Texas
41. HCC Service Delaware, LLC Delaware
42. HCC Specialty Holdings (No. 1) Limited United Kingdom
43. HCC Specialty Holdings (No. 2) Limited United Kingdom
44. HCC Specialty Insurance Company Oklahoma
45. HCC Specialty Insurance Holdings Ltd. United Kingdom
</Table>
<Table>
<Caption>
STATE OR COUNTRY OF
NAME INCORPORATION
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46. HCC Strategic Investments, LLC Delaware
47. HCC Trustees Limited United Kingdom
48. HCC Underwriters, A Texas Corporation Texas
49. HCCS Corporation Delaware
50. Houston Casualty Company Texas
51. Houston Casualty Company Europe, Seguros y Reaseguros, S.A Spain
52. Intellicare, Inc. Alabama
53. Interra, Inc. Indiana
54. Interra Reinsurance Group, Inc. Indiana
55. LDG Insurance Agency Incorporated Massachusetts
56. LDG Re (London) Ltd. United Kingdom
57. LDG Re Worldwide Limited Delaware
58. LDG Re Worldwide Limited United Kingdom
59. LDG Reinsurance Corporation Massachusetts
60. Loss Management, Inc. Delaware
61. Loss Management Services, Inc. Maryland
62. MAG Acquisition Sub, Inc. Delaware
63. Manchester Dickson Holdings, Limited United Kingdom
64. Marshall Adjusting Corp. New York
65. Marshall Rattner, Inc. New York
66. Merger Sub, Inc. Texas
67. National Insurance Underwriters Arkansas
68. PEPYS Holdings Limited United Kingdom
69. PEPYS Management Services Limited United Kingdom
70. Premier Risk Services Limited United Kingdom
71. Professional Indemnity Agency, Inc. New Jersey
72. Professional Indemnity Agency, Inc. of N.Y New York
73. Profind Insurance Services Limited United Kingdom
74. Rattner Mackenzie (Bermuda) Ltd. Bermuda
75. Rattner Mackenzie Limited United Kingdom
76. Rattner Mackenzie Insurance Services (Guernsey) Ltd. Guernsey
77. Rattner Mackenzie Limited (RML) (Exempted) Co. Jordan
78. Rattner Mackenzie Limited (North America), Inc. New York
79. Rockwood Acquisition Corporation Delaware
80. SBS Insurance Holdings, A Texas Corporation Texas
81. Select Benefits, Inc. Indiana
82. Signal Aviation Insurance Services, Inc. Nevada
83. Specialty Reinsurance Intermediaries, Inc. Massachusetts
84. Specialty Insurance Underwriters, Inc. Missouri
85. Specialty Surety & Insurance Services, LLC California
86. Surety Associates Holding Co., Inc. New Mexico
87. The Centris Group, Inc. Delaware
88. The Schanen Consulting Group, LLC Georgia
89. The Wheatley Group, Ltd. New York
90. TMD Rattner, L.L.C New York
91. TTR, LLC New York
92. U.S. Specialty Insurance Company Texas
93. US Holdings, Inc. Delaware
94. USBenefits Insurance Services, Inc. California
95. VASA Brougher, Inc. Indiana
96. VASA Insurance Group, Inc. Indiana
97. VASA North America, Inc. Indiana
</Table>