Men who have sex with men (MSM) account for the largest number of persons diagnosed with AIDS in the USA, with higher than average rates of drug use and unprotected sex being cited as the principal reasons underlying their high rates of HIV infection. Recent evidence has suggested that the use of websites specifically designed to promote unsafe sexual practices may be particularly common among MSM, thereby fostering their risky behaviours. In light of these findings, the present study is based on a content analysis of 1316 ads/profiles posted on one of the most popular MSM websites that specifically fosters unprotected sex. Ads/profiles were selected randomly based on the American ZIP code of residence. Data were collected between September 2006 and January 2007. Rates of advertised for high-risk sexual behaviours were very high, particularly for oral sex involving ejaculation into the mouth (88.0% for receptive oral sex, 77.4% for insertive oral sex), anal sex involving ejaculation into the anus (79.7% for insertive anal sex, 69.4% for receptive anal sex), multiple partner sex (77.9%) and felching (16.5%). A multivariate analysis of the correlates of sexual risk preferences identified seven factors that were related to a propensity towards enhanced sexual risk: younger age (β = 0.12, P = 0.0001), not being African American (β = 0.05, P = 0.0341), self-identification as a sexual ‘bottom’ (β = 0.20, P = 0.0001), not caring about one’s potential sex partners’ HIV serostatus (β = 0.15, P = 0.0001), preferring to have sex while under the influence of drugs (β = 0.08, P = 0.0022), a greater involvement in and commitment to the use of the website to locate potential unprotected sex partners (β = 0.16, P = 0.0001) and not being HIV-negative (β = 0.08, P = 0.0081). The HIV intervention-related implications of these findings are discussed.