This study compared healthcare utilization by injection drug users (IDUs) and non-IDUs. Data were abstracted from patients’ medical records, admitted on HIV/AIDS treatment centers, between 1986 and 2002, forming a non-concurrent cohort study. Variables included: sociodemographics, HIV/AIDS exposure group, healthcare utilization (consultations, procedures, and prescriptions). Descriptive analyses included ageperiod and cohort effects. Out of 170 patients, with an average age of 30 years, 39.4% were IDUs, 71.8% were males and had low levels of education. At the first consultation, 86.5% neither received an ARV prescription nor had a request for CD4 or viral load. Injection drug users, as com- pared to non-IDUs, were less likely to receive ARV prescriptions and requests for CD4 lymphocyte and viral load counts, even though the number of consultations did not differ between the two groups. Healthcare utilization increased in calendar-year in the non-IDUs group, parallel to the implementation of the Brazilian health policy of universal care. However, this favorable trend was not observed among IDUs. Differential outcomes for HIV/AIDS among IDUs, towards worse prognosis, suggest difficulties in terms of adherence and follow-up of ARV therapy in this population.