A total of 107 HIV-1 isolates from untreated adult patients recruited in Abidjan, CMte d'Ivoire, in 2001 and 2002 were sequenced in the env, reverse transcriptase (RT), and protease genes. The results show that CRF02_AG is still predominant in this west African population; key mutations of resistance to antiretroviral drugs (NRTI, NNRTI, and PIs) were detected in 5.6% of the patients. We hypothesize that these resistant mutants have been acquired through horizontal transmission. Compared to a previous study carried out by our group in 1997-2000 in a similar population of Abidjan, it seems that there is a dynamic process of resistance and that a survey will be necessary.