This study reports the analysis of human immunodeficiency virus type 1 (HIV‐1) protease (PR) and reverse transcriptase (RT) coding sequences from 136 HIV‐1‐infected subjects from Chile, 66 (49%) of them under antiretroviral (ARV) treatment. The prevalence of mutations conferring high or intermediate resistance levels to ARVs was 77% among treated patients and 2.5% among drug‐naïve subjects. The distribution of resistance prevalence in treated patients by drug class was 61% to nucleoside RT inhibitors, 84% to nonnucleoside RT inhibitors, and 46% to PR inhibitors. Phylogenetic analysis revealed that 115 (85%) subjects were infected with subtype B viruses, 1 with a subtype F1 virus, and 20 (15%) carried BF intersubtype recombinants. Most BF recombinants grouped into two clusters, one related to CRF12_BF, while the other could represent a new circulating recombinant form (CRF). In conclusion, this is the first report analysing the prevalence of ARV resistance which includes patients under HAART from Chile. Additionally, phylogenetic analysis of the PR–RT coding sequences reveals the presence of BF intersubtype recombinants. J. Med. Virol. 79: 647–656, 2007. © 2007 Wiley‐Liss, Inc.