AMENDED: Dosing will proceed for 104 weeks at each dose level. Original design: Five patients are treated at the initial dose level. Because ddI is not stable in the acid environment of the stomach, oral doses of ddI follow administration of an antacid. An alternative method of dosing is to mix the reconstituted ddI with an appropriate volume of Maalox TC or Mylanta II. In order to determine the MTD, successive groups of 5 patients enter the study at a higher dose level after 3 patients have experienced 3 weeks of dosing and significant toxicities have not developed. Patients are assigned to treatment groups in the order in which they are enrolled. Dosing proceeds for 16 weeks at each dose level. However, consideration is given to escalating patients entered at the lowest dose to the next dose level after 10 weeks of dosing. The dose escalation continues until toxicities requiring dose modifications are found in 2 of 5 in any group.