This paper describes a preliminary study aimed at testing the efficacy of a brief medication counselling and behavioural intervention in improving adherence to combination antiretroviral medication therapy and prophylactic treatment among non-adherent men living with HIV. Twenty-one non-adherent HIV-positive men obtaining primary care clinical services at a Veterans Affairs Medical Center were recruited by health care providers. Intervention participants were primarily African-Americans with histories of intravenous drug use. During a period of five months, participants were provided with monthly medication counselling and a weekly medication pill organizer. Participants were compared with 21 non-adherent matched controls receiving standard pharmacy care including review of medications. Intervention and control subjects were compared on several variables: medication refill timeliness, appointment attendance, hospitalizations and opportunistic infections. Medical information was obtained from hospital and pharmacy records at baseline and post-intervention. Pre- to post-intervention rates of adherence to medication refills and clinic appointments increased significantly among intervention participants. Relative to matched controls, intervention participants also significantly increased drop-in visits and showed fewer hospitalizations. Intervention participants also showed significant decreases in the number of opportunistic infections. Results suggest that exposure to medication counselling and behavioural interventions increase adherence, with associated reductions in negative clinical outcomes.