We aimed to determine the prevalence of HIV infection and associated risk factors among Montrealers of Haitian origin. We carried out a voluntary, anonymous survey in 7 primary care medical clinics in Montreal among 5039 persons aged 15 to 49 years born in Haiti or with at least one parent born in Haiti. The participation rate was 94.3%. Overall, HIV prevalence was 1.3% (1.6% in men and 1.1% in women). The HIV prevalence was lower among those born in Canada or who had resided in Canada longer. The prevalence among subjects who had travelled to Haiti in the previous 5 years was 2.0%, twice the rate of those who had not. The adjusted population attributable fraction of HIV infections associated with having had unprotected sex in Haiti was 10.2%. This study identified risk factors which will help in the design of more effective prevention programmes among Montrealers of Haitian origin.