In order to evaluate the occurrence of hepatotoxicity in patients treated with antiretroviral therapy (ART) who switch protease inhibitor (PI), and the role of viral hepatitis in its development, we performed a retrospective study on 182 HIV patients treated with ART for 24 months. The presence of hepatitis viruses and alanine transaminase levels were evaluated. Hepatotoxicity developed in a low number of subjects without co-infection, but was significantly higher in co-infected patients (14/51 versus 62/131, P = 0.01). Ritonavir was associated with higher rates of severe hepatotoxicity in the co-infected group. Patients presenting any problems related to ART, including the development of hepatotoxicity, continued therapy by switching PI. The occurrence of hepatotoxicity with second/third choice PIs, including ritonavir, remained stable. Our results suggest that switching PI does not increase the occurrence of drug-related liver toxicity.