The immunovirological outcome of lopinavir/ritonavir was evaluated in 70 antiretroviral-experienced HIV patients; at baseline, median CD4+ cell count was 218 cells/mm(3) and median plasma viraemia 4.58 log(10) copies/mL. After 12 months, we observed an increase in CD4+ cell count to 322 cells/mm(3) (P = 0.0001) and a decrease in plasma viraemia to 2.35 log(10) copies/mL (P = 0.0001). Four patients discontinued lopinavir/ritonavir during observation. Among metabolic parameters, only triglyceride concentrations increased during treatment (P = 0.02). Twenty-six patients had a genotypic resistance test at baseline; four had > or =6 mutations known to reduce susceptibility to lopinavir/ritonavir. Undetectable plasma viraemia was obtained only in patients with < or =5 mutations (61.9%).