Tipranavir (TPV) is a nonpeptidic protease inhibitor with potent in vitro activity against most HIV-1 strains resistant to other protease inhibitors. In vitro data have shown that resistance to TPV develops slowly. When coadministered with ritonavir (RTV) as a booster, TPV has shown potent antiviral activity in multiple antiretroviral-experienced patients. In the RESIST-1 and RESIST-2 studies, the efficacy and safety of TPV/RTV (500/200 mg twice daily) in highly treatment-experienced HIV-1-positive patients was assessed. Analysis at 48 weeks showed that TPV/RTV-containing regimens significantly improved immune and virological responses compared with a RTV-boosted comparator protease inhibitor plus optimized background regimen. TPV is generally well tolerated; nevertheless, clinical hepatitis and liver decompensation have been associated to its use, together with an indication of an increased risk of intracranial hemorrhage. Extensive listing of drug-drug interactions have been reported with TPV.