OBJECTIVE: We describe medium-term outcomes for young children receiving antiretroviral therapy (ART) in resource-limited countries. METHODS: Analyses were conducted on surveillance data for children <5 years of age receiving ART (initiated April 2002 to January 2008) in 48 HIV/AIDS treatment programs in Africa and Asia. Primary outcome measures were probability of remaining in care, probability of developing World Health Organization stage 4 clinical events, rate of switching to second-line ART, and drug toxicity, compared at 6, 12, 24, and 36 months of ART. RESULTS: Of 3936 children (90% in Africa) initiating ART, 9% were <12 months, 50% were 12 to 35 months, and 41% were 36 to 59 months of age. The median time of ART was 10.5 months. Probabilities of remaining in care after 12, 24, and 36 months of ART were 0.85, 0.80, and 0.75, respectively. Compared with children 36 to 59 months of age at ART initiation, probabilities of remaining in care were significantly lower for children <12 months of age. Overall, 55% and 69% of deaths and losses to follow-up occurred in the first 3 and 6 months of ART, respectively. Probabilities of developing stage 4 clinical events after 12, 24, and 36 months of ART were 0.03, 0.06, and 0.09, respectively. Only 33 subjects (0.8%) switched to second-line regimens, and 151 (3.8%) experienced severe drug toxicities. CONCLUSIONS: Large-scale ART for children <5 years of age in resource-limited settings is feasible, with encouraging clinical outcomes, but efforts should be increased to improve early HIV diagnosis and treatment.