The international performance of the US reinsurance industry differed sharply from other segments of the US financial services sector in the latter half of the twentieth century. Trade imbalances and loss ratios in international reinsurance business indicate that the American reinsurance industry had pronounced difficulties in getting a foothold in international markets. The dominance of the established western European reinsurance centres, which prevailed throughout the early phases of American reinsurance, continued long into the post-war period. Moreover, bilateral trade with the world's foremost reinsurance centre, London, failed to compensate for American catastrophe losses, a task maintained by reinsurers to be the key function of their international activities. London's failure to perform adequately is described by analysing the underwriting results of the period before and after Hurricane Betsy, the major American catastrophe loss of the 1960s.