['Directly administered antiretroviral therapy (DAART) in methadone clinics has the potential to improve treatment outcomes for human immunodeficiency virus (HIV)-infected injection drug users (IDUs).', 'DAART was provided at 3 urban methadone clinics. Eighty-two participants who were initiating or reinitiating highly active antiretroviral therapy (HAART) received supervised doses of therapy at the clinic on the mornings on which they received methadone. Treatment outcomes in the DAART group were compared with outcomes in 3 groups of concurrent comparison patients, who were drawn from the Johns Hopkins HIV Cohort. The concurrent comparison patients were taking HAART on a self-administered basis. The 3 groups of concurrent comparison patients were as follows: patients with a history of IDU who were receiving methadone at the time HAART was used (the IDU-methadone group; 75 patients), patients with a history of IDU who were not receiving methadone at the time that HAART was used (the IDU-nonmethadone group; 244 patients), and patients with no history of IDU (the non-IDU group; 490 patients).', 'At 12 months, 56% of DAART participants achieved an HIV type 1 RNA level <400 copies/mL, compared with 32% of participants in the IDU-methadone group (P=.009), 33% of those in the IDU-nonmethadone group (P=.001), and 44% of those in the non-IDU group (P=.077). The DAART group experienced a median increase in the CD4 cell count of 74 cells/mm3, compared with 21 cells/mm3 in the IDU-methadone group (P=.04), 33 cells/mm3 in the IDU-nonmethadone group (P=.09), and 84 cells/mm3 in the non-IDU group (P=.98). After adjustment for other covariates in a logistic regression model, DAART participants were significantly more likely to achieve viral suppression than were patients in each of the 3 comparison groups.'] Is directly administered antiretroviral therapy in methadone clinics associated with improved HIV treatment outcomes , compared with outcomes among concurrent comparison groups?