West African adults with warning signs of failure of antiretroviral treatment (ART) at 6 months were assessed for the probability and factors associated with success at 36 months. After 6 months on ART, patients were included if they had a bad immunologic response (BIR) (month 6 CD4 count < pre-ART CD4 count + 50/mm(3)), incomplete virologic suppression (IVS) (month 6 plasma HIV-1 RNA >300 copies/ml), or both (Dual). They were followed for 30 months after inclusion. CD4 counts and HIV-1 RNA were measured every 3 months. We estimated the probability of reaching immunovirologic success (CD4 count >350/mm(3) and plasma HIV-1 RNA <300 copies/ml) and looked for determinants using Cox analysis. A total of 208 adults were included. Among patients in the IVS and Dual groups, 23% and 38% had at least one genotypic resistance mutation at month 6. The 36-month cumulative probability of immunovirologic success was 0.84 in BIR, 0.81 in IVS, and 0.67 in Dual (p = 0.02). Adjusting for CD4 count, viral load, ART regimen, and morbidity, patients who had no genotypic resistance mutations at month 6 or a medication possession ratio (MPR) >90% between month 6 and month 36 had a likelihood of success 3.8 and 3.6 higher than other patients. The 36-month probability of success was 0.56 and 0.86 in patients with an MPR <90% and >90% and 0.59 and 0.84 in patients with and without resistance. After warning signs of failure at 6 months, a large proportion of patients reaches immunovirologic success before 36 months provided there is a high rate of adherence to medication and the absence of early resistance mutations.