Sustained-release morphine (SRM) was studied in patients with acquired immune deficiency syndrome (AIDS)-related chronic pain. Outpatients and inpatients with AIDS-related pain were studied for 3-18 days in an open label prospective survey. Patients were stratified according to prior opioid analgesic use for the purpose of initiating and titrating SRM, which was administered at a 12-hr interval. Immediate-release morphine (IRM) was offered every 2 hr as needed for supplemental analgesia at one-quarter to one-third of the 12-hourly SRM dose. Pain intensity (PI), quality of life (QL), acceptability of therapy (AT), side effects, safety, and morphine usage were evaluated. of 44 patients enrolled, 40 (91%) were evaluated for intent-to-treat analysis, and 24 (55%) completed the study. PI decreased by 50% (from severe to mild-moderate) in the intent-to-treat patients and by 65% (from severe to mild) in the completed patients. QL was fair to good in 80% and poor in 20% of both groups. AT was good to excellent in 78% of the intent-to-treat and in 96% of the complicated patients. Of 61 adverse events reported, 61% required intervention, and 92% were resolved. Total morphine dose remained stable while IRM dosage and frequency of use significantly decreased with escalation of the SRM dose. A significant reduction in PI was achievable with SRM in a variety of painful conditions experienced by AIDS patients, with limited or manageable side effects in most. This study supports the usefulness of opioid analgesia for severe pain in AIDS.