Alternative and less toxic treatments need to be investigated for the treatment of HIV infection. Studies have shown that the dideoxynucleosides ddI and ddC may be effective antiretroviral agents in the treatment of HIV-infected individuals. However, ddI and ddC have yet to be compared on the basis of patient survival, drug tolerance, immunologic and virologic effectiveness, and the incidence of opportunistic infection or opportunistic malignancy. Results of this study will yield information regarding the relative therapeutic benefits and toxicities of each drug while providing alternative treatment to patients who are unable to tolerate or have had progression of disease while on AZT.