OBJECTIVES:  This study sought to estimate the average outpatient cost of providing adult antiretroviral therapy (ART) at an urban care centre for the first year following ART initiation. METHODS:   A retrospective, ingredients-based costing approach was implemented, as previously described in literature. Medical records for a convenient sample of 120 patients were reviewed 1 year after ART initiation. Subjects were assigned to any one of the following outcome categories based on their status at the end of the study period: in care and responding (IC); in care but not responding (NR); or no longer in care at study site (NIC). Average cost per outcome category was estimated based on resource utilisation, in 2013 US$ RESULTS:   The overall annual retention in care was 93.3%. At the end of the first 12 months of ART care, 109 (90.8%) of the patients were IC, 7 (6.7%) patients were NIC and 3 (2.5%) patients were NR. The average outpatient cost per patient initiated was USD $461.  The costs were structured as follows; outpatient visits (49.2%), medications (26.4%), laboratory tests (21.8%) and fixed costs (2.6%). The average cost to produce an IC patient was US$ 472, NR US$ 438 and NIC US$ 322. The average cost of producing a patient in care and responding to ART represented 49.2% of the country’s GDP per capita for 2013. This estimate excludes building and utility costs because they were unavailable, hence the actual average cost may be higher. CONCLUSIONS: These findings show that maintaining an HIV/AIDS patient in care and responding to ART is an expensive undertaking relative to the country’s GDP per capita. This underscores the need for periodic costing studies as a way of continually monitoring the costs and cost structures associated with caring for people living with HIV and AIDS, as this would aid in planning and decision-making.