Inclusion Criteria: - Patients with a confirmed diagnosis of AIDS - having a Performance score of 0, 1, or 2 (patients' ability to perform daily activities, a score ranging from 0 [fully active, no disease restriction] to 3 [capable of only limited self-care, confined to bed or chair more than 50% of waking hours]) - taking a maintenance dose of AZT of at least 400 mg/day - having a hematocrit of at least 30% and a history of a >=15% decrease in hematocrit since starting AZT therapy, or have become dependent on transfusions - who are clinically stable for at least 1 month before study entry.