Both hemophiliacs and non-hemophiliacs take AZT for a period of 12 weeks. The first dose is administered intravenously. AZT is then given orally every 4 hours while awake (5 doses per day). Patients are evaluated by physical examinations and laboratory assessments. These include HIV culture of blood and leukocyte counts, lymphocyte counts, and lymphocyte subsets measured at study entry and every 4 weeks thereafter. Patients are hospitalized for pharmacokinetic studies at study entry and at Weeks 6 and 12. Each of these studies involves both intravenous and oral administration within 48 hours of one another. Blood is sampled at 0, 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 hours after each administration and urine is collected every 2 hours for 12 hours.