A Double-Blind, Randomized, Comparative Study of Delavirdine Mesylate (U-90152S) in Combination With Didanosine (ddI) Versus ddI Alone in HIV-1 Infected Individuals With CD4 Counts of <= 300/mm3

Inclusion Criteria Concurrent Medication: Allowed: * AZT. Patients must have: * HIV-1 seropositivity. * CD4 count \<= 300 cells/mm3. * No active or acute (onset within the past month) opportunistic infections such as active cryptococcosis, pneumocystis carinii, herpes zoster, histoplasmosis, or cytomegalovirus (CMV). * Consent of parent or guardian if less than 18 years of age. * Understanding of potential risk to fetus related to study participation. * Acceptable medical history, physical exam, EKG, and chest x-ray during screening. NOTE: * Patients with cutaneous Kaposi's sarcoma requiring no systemic therapy are permitted. Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: * Active tuberculosis that is sensitive to rifampin. * Inability to swallow numerous tablets. * Clinically significant active or acute medical problems, including progressive multifocal leukoencephalopathy, lymphoma, or malignancy requiring systemic therapy. * Clinically significant hypersensitivity to piperazine-type drugs (e.g., Antepar and Stelazine). * Grade 2 or worse baseline organ function. NOTE: * Hemophiliacs with grade 2 bilirubin, alkaline phosphatase, SGOT, or SGPT will be considered if these values have been stable over the past year. NOTE: * Patients with suspected Gilbert's syndrome will be considered if bilirubin is grade 2 or better. Patients with the following prior conditions are excluded: * History of pancreatitis within the past 2 years. * History of clinically significant nervous system or muscle disease, seizure disorder, AIDS dementia, or psychiatric disorder that would preclude study compliance. * History of grade 2 or worse peripheral neuropathy. * Intolerance to ddI in previous treated patients. Prior Medication: Excluded: * More than 4 months total of prior ddI. * Any prior ddC, d4T, or 3TC. * Prior nonnucleoside reverse transcriptase inhibitors, including L-drugs, nevirapine, TIBO, HEPT, delavirdine, atevirdine, and alpha-APA. * Other investigational antiretroviral medications (including foscarnet) or immunomodulators (including all interferons) within 21 days prior to initial study drug dose. * Prior prophylactic or therapeutic HIV-1 gp120 or 160 vaccines. * Rifampin, rifabutin, astemizole, loratadine, or terfenadine within 21 days prior to initial study drug dose. * Any unapproved investigational medication for any indication within 21 days prior to initial study drug dose. Required: * AZT therapy at some time prior to screening. Active substance abuse.