The goal of this study was to describe and compare the prevalence, predictors and patterns of marijuana use, specifically medicinal marijuana use among patients with HIV in Ontario, Canada. Any marijuana use in the year prior to interview and self-defined medicinal use were evaluated. A cross-sectional multicenter survey and retrospective chart review were conducted between 1999 and 2001 to evaluate overall drug utilization in HIV, including marijuana use. HIV-positive adults were identified through the HIV Ontario Observational Database (HOOD), 104 consenting patients were interviewed. Forty-three percent of patients reported any marijuana use, while 29% reported medicinal use. Reasons for use were similar by gender although a significantly higher number of women used marijuana for pain management. Overall, the most commonly reported reason for medicinal marijuana use was appetite stimulation/weight gain. Whereas male gender and history of intravenous drug use were predictive of any marijuana use, only household income less than $20,000 CDN was associated with medicinal marijuana use. Age, gender, HIV clinical status, antiretroviral use, and history of intravenous drug use were not significant predictors of medicinal marijuana use. Despite the frequency of medicinal use, minimal changes in the pattern of marijuana use upon HIV diagnosis were reported with 80% of current medicinal users also indicating recreational consumption. Although a large proportion of patients report medicinal marijuana use, overlap between medical and recreational consumption is substantial. The role of poverty in patient choice of medicinal marijuana despite access to care and the large proportion of women using marijuana for pain constitute areas for further study.