Tipranavir is the most recently introduced protease inhibitor for the suppression of the human immunodeficiency virus (HIV). A selective reversed-phase liquid chromatographic assay, previously developed for atazanavir, has been extended and validated for tipranavir in plasma. Compounds were isolated from a 500 microL plasma sample using liquid-liquid extraction with dichloromethane. After evaporation and reconstitution of the extract the sample was analysed using reversed-phase liquid chromatography and ultra violet detection at 280 nm. In the evaluated concentration range (0.2-50 microg/mL tipranavir), intra-day precisions were <or=8% and inter-day precisions were <or=10%. Accuracies between 95 and 108% were found. The clinical applicability of the assay was demonstrated in an HIV-infected patient who ingested 500 mg tipranavir bid in combination with 100 mg ritonavir.