BACKGROUND There is a common belief that injecting drug use (IDU) is associated with lower uptake, retention and success of antiretroviral treatment (ART) in human immunodeficiency virus (HIV)-infected patients. We examined this in an Indonesian setting, where IDU is the main risk factor for HIV infection. METHODS Patient characteristics and response to ART were recorded for all patients diagnosed with HIV infection in the referral hospital for West Java (40 million people). Kaplan-Meier estimates and Cox's regression were used to compare mortality, loss to follow-up and virological failure between patients with and without a history of IDU. RESULT A total of 773 adult HIV patients (81.9% IDUs) presented between January 1996 and April 2008. IDUs had a median CD4 cell count of 33 [interquartile ratio (IQR), 12-111] cells/mm(3) compared to 84 (IQR, 28-224) cells/mm(3) in non-IDUs. Among patients with a history of IDU, 87.7% were coinfected with hepatitis C (HCV). Mortality was associated strongly with CD4 count; after 6 months of ART, 18.3, 20.3, 7.1 and 0.7% of patients with CD4 cell counts <25, 25-99, 100-199, respectively, > or =200/mm(3) had died (P < 0.0001). Mortality [adjusted for CD4; hazard ratio (HR) = 0.65; 95% confidence interval (CI) 0.35-1.23], loss to follow-up (HR = 0.85, 95% CI 0.51-1.41) and virological failure (HR = 0.47, 95% CI 0.19-1.13) were not significantly different in IDUs and non-IDUs. CONCLUSION Intravenous drug users (IDUs) in Indonesia with HIV/acquired immune deficiency syndrome tend to have more advanced disease but respond similarly to non-IDUs to antiretroviral therapy.