['To examine the role of antiretroviral treatment related perceptions relative to other clinical and psychosocial factors associated with sexual risk taking in HIV positive men who have sex with men (MSM).', 'Participants were recruited from ambulatory HIV clinics in Montreal. Information on sociodemographic factors, health status, antiretroviral treatment related perceptions, and sexual behaviours was collected using a self administered questionnaire. At-risk sexual behaviour was defined as at least one occurrence of unprotected insertive or receptive anal intercourse in the past 6 months. Multivariate logistic regression was performed to evaluate the associations between at-risk sexual behaviour and covariates.', '346 subjects participated in the study. Overall, 34% of subjects were considered at risk; 43% of sexually active subjects (n=274). At-risk sexual behaviour was associated with two antiretroviral treatment related perceptions: (1) taking antiretroviral treatment reduces the risk of transmitting HIV (adjusted odds ratio (OR), 2.10; 95% confidence interval (CI), 1.16 to 3.80); and (2) there is less safer sex practised by MSM because of HIV treatment advances (OR, 1.82; CI, 1.14 to 2.90). Other factors, however, were more strongly associated with risk. These were: (1) safer sex fatigue (OR, 3.23; CI, 1.81 to 5.78); (2) use of "poppers" during sexual intercourse (OR, 6.28; CI, 2.43 to 16.21); and (3) reporting a greater proportion of HIV positive anal sex partners, compared with reporting no HIV positive anal sex partners: (a) <50% HIV positive (OR, 16.79; CI, 4.70 to 59.98); (b) > or =50% HIV positive (OR, 67.67; CI, 15.43 to 296.90).'] Is hIV status of sexual partners more important than antiretroviral treatment related perceptions for risk taking by HIV positive MSM in Montreal , Canada?