RT Journal Article SR Electronic T1 S11.1 Sexual Behaviour in Britain in the New Millennium: A New Era? JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP A17 OP A18 DO 10.1136/sextrans-2013-051184.0054 VO 89 IS Suppl 1 A1 Mercer, C H YR 2013 UL http://sti.bmj.com/content/89/Suppl_1/A17.4.abstract AB Background In 2001, Britain’s second National Survey of Sexual Attitudes and Lifestyles (Natsal-2) demonstrated increased sexual risk behaviour in contrast to Natsal-1, undertaken a decade earlier. STI diagnoses also increased between the mid-1990s and the mid-2000s, but since then, increases have been more modest. These trends coincided with changes in sexual health policy and practise in Britain, resulting in greater STI testing and the use of more sensitive diagnostic tests, making STI surveillance data less indicative of risk behaviour. This paper reviews a range of evidence to examine whether, and if so how, sexual behaviour has changed in Britain since the start of the millennium. Methods Analyses of routine data (including STI surveillance data, census data), general population surveys (including Natsal, Health Survey for England 2010 (HSE-2010), British Social Attitudes surveys), and community surveys of men-who-have-sex-with-men (MSM, including London’s Gay Men’s Sexual Health Surveys). Results Demographic trends support the limited sexual behaviour data collected experimentally by HSE-2010 suggesting that increases in heterosexual risk behaviour observed between 1990 and 2000 have not been sustained since 2000. At the same time, there has been increasing tolerance in Britain of more diverse sexual lifestyles, with public attitudes towards homosexuality increasingly liberal. While the population prevalence of recent same-sex behaviour in 2010 remains around 2–3%, among MSM, the proportion reporting high-risk sexual practises continues to rise, especially among HIV-positive MSM, as evident from increasing HIV incidence and STI outbreaks among this core-group. Conclusions Increases in sexual risk behaviour among MSM in Britain have clearly been observed since 2000, however, definitive conclusions regarding changes in heterosexual behaviour are limited until methodologically-comparable data are available from Natsal-3. These new data will enable us to better examine hypotheses regarding changes in the British population’s sexual behaviour across time and across the life-course.