Study A: Individuals who are infected with HIV can benefit from therapy with an effective anti-AIDS virus agent. ZDV is a potent inhibitor of HIV in vitro (test tube) and is safe in humans at the dose planned. It may be effective in preventing the development of AIDS or ARC in hemophiliacs who have the HIV antibody in their blood. The pharmacokinetic studies are especially important because the high prevalence of hepatic disease in this population may affect the metabolism and blood levels of ZDV.