A Randomized, Multicenter, Double-Blind, Phase III, Parallel Study of Zidovudine (AZT) Alone Versus AZT Plus Zalcitabine (Dideoxycytidine; ddC) Versus AZT Plus Saquinavir Mesylate (Ro 31-8959 ; HIV Proteinase Inhibitor) Versus AZT Plus ddC Plus Ro 31-8959 in Previously Untreated or Minimally Pretreated HIV-Infected Patients With CD4 Lymphocyte Counts From 50 to <= 350 Cells/mm3

Inclusion Criteria Concurrent Medication: Allowed: Erythropoietin and G-CSF. Concurrent Treatment: Allowed: Local skin radiotherapy. Patients must have: HIV infection. CD4 count 50 - 350 cells/mm3. No prior antiretroviral therapy OR less than 16 weeks of prior AZT. No acute serious opportunistic infections requiring immediate treatment. No unexplained fever persisting for 14 days within 90 days prior to study entry. No significant unexplained diarrhea persisting for 14 days within 30 days prior to study entry. No visceral Kaposi's sarcoma or lymphoma currently requiring chemotherapy and/or radiotherapy. Life expectancy of at least 80 weeks. Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: Malabsorption. Severe chronic diarrhea. Inadequate oral intake (unable to eat one or more meals daily because of chronic nausea, emesis, or abdominal/oral-esophageal discomfort). Any grade 3 or worse toxicity. Inability to comply with study requirements. Concurrent Medication: Excluded: Other investigational agents. Antineoplastic agents. Biologic response modifiers (including interferons). Foscarnet. Anti-HIV drugs other than the study drugs. Concurrent Treatment: Excluded: Radiotherapy (other than local skin radiotherapy). Patients with the following prior condition are excluded: History of non-Hodgkin's lymphoma. Prior Medication: Excluded: Acute therapy for opportunistic infection within 14 days prior to study entry. Prior HIV proteinase inhibitor.