Objectives: The aim of the study was to identify and describe the characteristics of persons born in the UK who acquire HIV infection abroad. Methods: Analyses using case reports and follow-up data from the national HIV database held at the Health Protection Agency were performed. Results: Fifteen per cent (2066 of 13891) of UK-born adults diagnosed in England, Wales and Northern Ireland between 2002 and 2010 acquired HIV infection abroad. Thailand (534), the USA (117) and South Africa (108) were the countries most commonly reported. As compared with UK-born adults acquiring HIV infection in the UK, those acquiring HIV infection abroad were significantly (P<0.01) more likely to have acquired it heterosexually (70% vs. 22%, respectively), to be of older age at diagnosis (median 42 years vs. 36 years, respectively), and to have reported sex with a commercial sex worker (5.6% vs. 1%, respectively). Among men infected in Thailand, 11% reported sex with a commercial sex worker. Conclusions: A substantial number of UK-born adults are acquiring HIV infection in countries with generalized HIV epidemics, and in common holiday destinations. Of particular concern is the high proportion of men infected reporting sex with a commercial sex worker. We recommend HIV prevention and testing efforts be extended to include travellers abroad, and that sexual health advice be provided routinely in travel health consultations and in occupational health travel advice packs, particularly to those travelling to high HIV prevalence areas and destinations for sex tourism. Safer sex messages should include an awareness of the potential detrimental health and social impacts of the sex industry.