Research has revealed differences on scales measuring HIV knowledge between individuals from various ethnic backgrounds and cultures. Few studies have examined this knowledge with immigrant populations and persons living with HIV. This study examined HIV knowledge among persons living with HIV who were either born in Canada or in sub-Saharan Africa and, for comparison, in a sample of college students. All participants were residing in Canada. Participants completed questionnaires measuring demographic variables, sexual health behaviour, and HIV status, treatment, and knowledge. Canadian-born patients living with HIV were more likely to be older and male than the other groups. On average, patients living with HIV were diagnosed 6.4 years ago, and 80% reported having current or previous experience taking HIV medications. After adjusting for age and gender, significant differences were found between the groups on the Brief HIV Knowledge Questionnaire. Canadian-born persons living with HIV (n = 110) scored higher than sub-Saharan African-born patients (n = 23) and college students (n = 81); mean percentage correct was 86, 70, and 62%, respectively (P < .01). These results suggested that ongoing HIV education is needed for all groups, and that additional tailored and targeted educational interventions are needed to address important gaps in knowledge among persons living with HIV patients originating from Africa and among college students.