There are few long-term data on ART-experienced patients in resource-limited settings. We performed a cross-sectional study of HIV-infected patients included in the ESTHER program in Calmette hospital, Phnom Penh, Cambodia, after 36 ± 3 months of cART. Therapeutic, clinical, and immunovirological outcomes were compared between patients who stated they were ART-naive (naive group), dual nucleoside reverse-transcriptase inhibitor (two-NRTI group), or fixed-dose combination of stavudine/lamivudine/nevirapine experienced (three-drug group) at entry to the program. A logistic regression model was used to evaluate the factors associated with virological failure (PCR HIV > 250 copies/ml). Among the 256 patients included in the analysis, 148 (58%) were ART naive while 50 (20%) had previously received two NRTIs and 58 (22%) three drugs. At entry to the program, all the patients received two NRTIs and one nonnucleoside reverse-transcriptase inhibitor (NNRTI). At evaluation, 46 patients (18%) were switched to a protease inhibitor-based regimen (9%, 32%, and 29% of the naive, two-NRTI, and three-drug groups; p < 0.0001). The median CD4 cell count increase was 180/μl overall (IQR: 96-276) and was higher in ART-naive than ART-experienced patients. In the intent-to-treat analysis, virological success was achieved in 83.5%, 67%, and 69% of the naive, two-NRTI, and three-drug groups, respectively (p = 0.002). Factors associated with virological failure were suboptimal previous ART exposure and WHO immunological failure criteria. The long-term efficacy of first-line cART is maintained in Cambodia. In ART-experienced patients, viral load monitoring needs to be available to establish early virological failure and preserve the potency of second line regimens.