The purpose of this study was to evaluate retrospectively the potential benefits of directly administered antiretroviral therapy (DAART) in HIV-infected former injecting drug users (ex-IDUs) admitted to residential drug rehabilitation facilities. We compared 106 of these patients consecutively admitted in 12 communities where DAART was administered (DAART group) to two matched control groups of ex-IDUs undergoing self-administered ART: 106 subjects in other 10 communities (SAT group) and 106 outpatients at hospital infectious-disease wards where community patients were referred after discharge (OUT group). We estimated the proportion of patients with high adherence and the hazard ratio (HR) of 20% or more increase in the CD4(+) cell count and of reaching an undetectable viral load. The proportion of patients with high adherence to treatment was highest in the DAART group. The probability of 20% or more increase in the CD4(+) cell count was significantly lower in the two control groups versus the DAART group (SAT group HR=0.32; OUT group HR=0.43). The HR of observing an undetectable HIV-RNA level versus DAART was significantly lower in the OUT group (HR: 0.71; 95% confidence interval [CI]: 0.52-0.97) but did not reach statistical significance for the SAT group (HR: 0.99; 95% CI: 0.74-1.33). Our findings after a 24-month follow-up, suggest that DAART in HIV-infected patients of drug-rehabilitation communities improves adherence, immunologic, and virologic outcome toward free outpatients. Even if our retrospective 36-month data do not show a prolonged viral suppression in these patients, DAART may be considered a valuable therapeutic and educational strategy in this particular target group.