: HIV-1 subtype B (54.4%) and subtype F (27.2%) are the most prevalent variants in patients who started antiretroviral therapy including an integrase inhibitor in the last 2 years in Northwest Spain. Virological response rates to antiretroviral therapy based on integrase inhibitor were significantly lower among F subtypes compared with B subtypes at weeks 12 (25.0% vs. 75.0%) and 24 (59.1% vs. 95.0%). Subtype F was independently associated with virological response at 24 weeks [odds ratio 11.8 (95% confidence interval 1.1-119.9); P = 0.037].