Chat room-based human immunodeficiency virus (HIV) prevention interventions are being implemented to reduce the risk of HIV exposure, infection and reinfection among men who have sex with men (MSM). However, little is known about how participants in chat room-based prevention interventions differ from their online non-participating peers. This analysis compared the baseline risk profiles of participants in an HIV prevention intervention ('active recruitment') to their chat room peers who did not participate in the intervention ('passive recruitment'). Data were collected using an online brief risk assessment from MSM (N = 448) who were recruited within Internet chat rooms. Mean age was 30 years. Half self-identified as Black or African American, 29% as White and 64% as gay. Compared with participants, non-participants were more likely to report: spending higher mean number of hours in online chat rooms; using condoms inconsistently during anal intercourse with a man met online during the past 3 months; having had an sexually transmitted disease; being HIV seropositive; using methamphetamines during the past 30 days and using drugs to enhance sexual satisfaction during the past 30 days. Although risk among MSM who use chat rooms remains high, those at greater risk may be those who are less likely to engage in online HIV prevention interventions.