The purpose of this study is to compare monotherapy to combination nucleoside analogue therapy in HIV+ persons without AIDS and with CD4 counts between 200 and 500/mm3. Patients will receive ZDV alone, ZDV + ddI, ZDV + ddC, or ddI alone. A decline in CD4 cell numbers to less than 50% of baseline values will be used as a landmark for evaluation in addition to clinical progression.