A range of doses of ddC is given to patients with AIDS and ARC. Eight patients with AIDS and eight patients with ARC are given ddC at the lowest level for 12 weeks. Patients who respond with a rise in their number of T4 cells or with a fall in HIV antigen in their serum (the fluid portion of the blood) are continued at that dose for an additional 12 weeks. Patients who do not respond at a given dose level (no rise in T4 or fall in serum HIV antigen) stop treatment at 12 weeks. All patients are followed off therapy for 4 weeks. As each dose level is found to be well tolerated for 10 weeks in five of the eight patients in each group, additional patients will be entered at higher dose levels until eight AIDS and eight ARC patients are receiving the drug at a given level.