A maximum tolerated dose (MTD) has been found in Phase I trials to date. An MED will be determined. The daily dose of d4T is divided into 2 portions and administered approximately 12 hours apart for 10 weeks. 5 patients receive the initial dose level and successive groups of 5 patients enter the study at a lower dose level once 3 patients in the preceding group have successfully completed at least 3 weeks of dosing and shown a positive effect on CD4 cell count and p24 antigen levels. The initial group of patients continue dosing at their dose level for an additional 94 weeks as long as they are doing well as measured by p24 antigen levels and CD4 cell counts. The dose de-escalation scheme continues until a lack of efficacy is seen in 2 of 5 patients in any group. Patients are assigned to de-escalating dose level treatment groups in the order in which they are enrolled. Blood and urine samples are taken regularly to check for toxic effects and therapeutic effectiveness. In each dosing group, 3 of 5 patients will be p24 antigen positive greater than or equal to 70 pg/ml, and 2 of 5 patients will have CDC-defined AIDS.