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