Pain is highly prevalent in individuals with HIV disease, yet is often overlooked as a symptom requiring clinical intervention. We evaluated the adequacy of analgesic management for pain and identified predictors of pain undertreatment in a sample of 366 ambulatory AIDS patients using a prospective cross-sectional survey design. Two hundred and twenty-six of the 366 ambulatory AIDS patients surveyed reported "persistent or frequent" pain over the 2 week period prior to the survey. Adequacy of analgesic therapy was assessed using the Pain Management Index (PMI - a measure derived from the Brief Pain Inventory) and the type and frequency of analgesic medications prescribed for pain. Results indicated that nearly 85% of patients were classified as receiving inadequate analgesic therapy based on the PMI. Less that 8% of the 110 patients who reported "severe" pain were prescribed a "strong" opioid (e.g., morphine), as suggested by published guidelines. Adjuvant analgesic drugs (e.g., antidepressant medications) were prescribed in only 10% of the patients. Women, less educated patients, and patients who reported injection drug use as their HIV transmission risk factor were most likely to have received inadequate analgesic therapy. These results demonstrate the alarming degree of undertreatment of pain in ambulatory patients with AIDS, and indicates the need to improve the management of AIDS-related pain in this underserved population. Future research should elucidate the factors that impede adequate pain management in order to overcome obstacles to adequate treatment.