The National Government HAART Program (NGP) for the provision of HAART to uninsured HIV-infected persons in Mexico began in 2001. The objective was to describe the virologic outcome of patients enrolled in the NGP in a large HIV treatment center in Mexico City. HIV-infected persons, naive or < or =6 months on HAART, who entered the NGP from 2001 to 2005 were included. Patients with virological suppression were compared to those with virologic failure (VF) during follow-up. Of 377 patients enrolled, 191 where eligible for analysis. The median age was 35.9 (18-75 years) and 85% were male. The median baseline CD4(+) T cell count was 183 cells/mm(3); 63.9% had <200 cells/mm(3) and/or an AIDS-defining event. During follow-up (median: 17.77 months), 55 patients (28.7%) changed their first regimen: 8.3% because of VF and the remaining due to toxicity. The probability of VF at 48 months was 20%. VF was associated with age <30 years (p = 0.003, RR 4.7, IC 95% 1.5-14.4). The use of NNRTI was associated with lower risk of VF (p = 0.042, RR 0.3, IC 95% 0.12-0.99). Nadir CD4(+) and AIDS-defining at baseline were not associated with VF. Implementation of NGP for HAART access in a specialized care setting in Mexico resulted in an excellent virologic response. Younger age was a significant risk factor for VF.