Patients are assessed and stratified according to liver function and severity of liver disease. Patients receive an intravenous (IV) dose of AZT on the first day of the study, followed by an oral dose 24 hours later on the second day of the study. Patients fast for 8 hours prior to each dose and for 2 hours after each dose. Liver function tests are repeated on the first day of the study. In each patient, serial measurements of serum and urine AZT and its metabolite, 3'-azido-3'-deoxy-5'-glucuronylthymidine (GAZT), are monitored after both doses.