In London, HIV-positive gay men appear to meet casual UAI partners of the same status through the Internet. This presents a risk for STI transmission. However, gay men were no more likely to meet casual UAI partners of unknown or discordant HIV status--which presents a risk for HIV transmission--online rather than offline.

Seeking sex on the Internet was associated with recent STD and high-risk sexual behaviour among HIV-positive and -negative gay men in London. The contribution of seeking sex on the Internet to the recent increase in high-risk behaviour among London gay men merits further investigation.