Patients with HIV infection or AIDS often receive several medications for treatment or prevention of their primary disease and/or associated complications. The objective of this study was to document patterns of drug use in an HIV-positive, outpatient population. Data were collected via one-on-one interviews with 26 HIV-positive patients; prescription and non-prescription drug use, adverse drug reactions and drug allergies were recorded. Anti-retroviral therapy was received by over 90 % of the patients. Over 90% of patients were on anti-infective agents, commonly cotrimoxazole or dapsone, while 27% received acyclovir. At least 70% of patients used three or more prescription medications concurrently. Every patient reported self-medicating with at least one over-the-counter (OTC) product and over half used three or more OTC products concurrently. Adverse reactions, mainly attributable to zidovudine, were reported by over 80% of patients. Non-compliance was a common drug-related issue; over 70% of patients omitted drug doses. In conclusion, the use of multiple medications in the ambulatory HIV-positive patients presents the health care team with potential drug-related problems that may ultimately affect the efficacy and toxicity of therapy. Thus pharmacists may play an active role in the provision of direct care to these patients.