Previous studies have shown that IFN-alpha can induce regression of Kaposi's sarcoma and suppression of HIV in some patients. Although various trials using IFN-alpha in combination with the nucleoside analogue zidovudine have demonstrated a high degree of antitumor activity and evidence of HIV suppression, the overlapping toxicity (primarily neutropenia) of these two agents has proven dose-limiting. The toxicity profile of ddI suggests that this drug may be better tolerated than zidovudine when combined with IFN-alpha.