OBJECTIVE: Thailand began a national antiretroviral (ARV) treatment program in 2000 and all government and some private and university hospitals now provide treatment to eligible HIV-infected patients. We describe program scale-up and patient outcomes from 2000 to 2007. METHODS: Data from 839 hospitals in all 76 provinces of Thailand were included in this analysis. Outcomes were assessed for patients initiating ARV treatment from January 2000 to December 2005. Follow-up data through March 2007 were included; lost to follow-up was defined as >3 months late for a follow-up visit. A Cox proportional hazard model was used to assess risk factors for death; the Kaplan-Meier method was used to estimate survival probabilities. RESULTS: Outcome data are reported for 58008 patients. Among these 52.2% were male; at treatment initiation the median age was 34 years the median CD4 count was 41 cells per cubic millimeter and 50.5% had AIDS. The initial regimen was nevirapine and 2 nonnucleoside reverse transcriptase inhibitors for 92.4% of patients; median follow-up time was 1.6 years (interquartile range = 0.8-2.4 years). Lost to follow-up occurred in 8.8% of patients. Overall 1-year survival was 0.89 (95% confidence interval = 0.88 to 0.89). Death was significantly associated with male sex age >40 years baseline CD4 count