A scheduled regimen of oral narcotic analgesics was compared with a regimen of oral narcotic analgesics plus ibuprofen for analgesic efficacy in patients with cancer. Ten patients with metastatic cancer were randomly assigned to receive either ibuprofen 400 mg or a look-like placebo 4 times daily in addition to each patient''s existing regimen of scheduled oral narcotics. A 2-period changeover study design was used. The 24-h narcotic intake equated to injectable morphine was computed for each patient at baseline and during the 9 study days. A visual analog scale was used to evaluate pain relief, nausea, mood depression, daytime drowsiness and nighttime sleeplessness. The analgesic efficacy of the narcotic-ibuprofen combination was significantly greater than the analgesic efficacy of the narcotic-placebo combination. Eight patients demonstrated a positive treatment effect with added ibuprofen; the overall improvement in analgesia averaged 39.1% in these patients. There was no significant increase from baseline in the incidence of nausea, mood depression, daytime drowsiness or nighttime sleeplessness. At the doses used in this study, a treatment regimen of oral narcotic analgesics plus ibuprofen was more effective than oral narcotics alone in relieving pain associated with cancer.