Exhibit 21.1 Subsidiaries of the Registrant Jurisdiction of Percentage Name Organization Ownership ---- ------------ --------- A.C.E. Insurance Company, Ltd. Bermuda 100% ACE London Group Limited United Kingdom 100% ACE Capital Limited United Kingdom 100% ACE Capital III Limited United Kingdom 100% ACE Capital IV Limited United Kingdom 100% ACE London Holdings Ltd. United Kingdom 100% ACE Capital II Ltd. United Kingdom 100% ACE London Investments Limited United Kingdom 100% ACE London Aviation Limited United Kingdom 100% ACE London Underwriting Limited United Kingdom 100% ACE Underwriting Services Limited United Kingdom 100% ACE London Services Limited United Kingdom 100% ACE Staff Corporate Member Limited United Kingdom 100% Methuen Group Limited United Kingdom 100% Methuen Holdings Limited United Kingdom 100% Methuen Europe Limited United Kingdom 100% Methuen Investments Limited United Kingdom 100% Methuen Limited United Kingdom 100% Methuen Services Limited United Kingdom 100% Methuen Systems Limited United Kingdom 100% Methuen Underwriting Limited United Kingdom 100% Underwriting Systems Limited United Kingdom 100% ACE Reinsurance Company Europe Ltd. Ireland 100% ACE Insurance Company Europe Ltd. Ireland 100% Corporate Officers & Directors Assurance Ltd. Bermuda 100% Oasis Real Estate Co. Ltd. Bermuda 100% Scarborough Property Holdings, Ltd. Bermuda 40% Tripar Partnership Bermuda 100% ACE Insurance Management Ltd. Bermuda 100% ACE Realty Holdings Ltd. Bermuda 100% ACE Services Ltd. Cayman Islands 100% ACE US Holdings, Inc. USA (Delaware) 100% ACE Strategic Advisors Inc. USA (Delaware) 100% ACE USA, Inc. USA (Delaware) 100% Industrial Excess & Insurance Brokers USA (California) 100% Industrial Underwriters Insurance Co. USA (Texas) 100% CRC Creditor Resources Canada Limited Canada (British Columbia) 60% Rhea International Marketing (L), Inc. Malaysia 60% Westchester Fire Insurance Company USA (New York) 100% Westchester Surplus Lines Insurance Co. USA (Georgia) 100% Westchester Specialty Insurance Services Inc. USA (Nevada) 100% Oasis Insurance Services Ltd. Bermuda 100% Oasis Investments Limited Bermuda 100% Oasis Personnel Limited Cayman Islands 100% Tarquin United Kingdom 100% ACE Capital V Limited United Kingdom 100% Charman Group Limited United Kingdom 100% Charman Underwriting Agencies Limited United Kingdom 100% Charman Trustees Limited United Kingdom 100% Tempest Reinsurance Company Limited Bermuda 100% CAT Limited Bermuda 100% Hamilton Services Limited Bermuda 100% 39