This 2 arm study will assess the effect of moderate liver impairment on the pharmacokinetics of saquinavir and ritonavir at steady state following administration of saquinavir/ritonavir 1000mg/100mg po bid in HIV patients. Saquinavir/ritonavir will be administered concomitantly with 2 to 3 active nucleoside reverse transcriptase inhibitors. The study will compare a group of HIV patients without known liver disease and a group with moderate liver disease. The anticipated time on study treatment is <3 months, and the target sample size is <100 individuals.