The effect of the regular administration of ibuprofen on pain following abdominal surgery was investigated in a double-blind placebo-controlled study. The analgesic action of ibu-profen was measured by a reduction in the amount of morphine self-administered from an On-Demand Analgesic Computer. Pain scores, nausea scores and blood loss were similar in both groups, but patients receiving ibuprofen de-manded significantly less morphine in the 24 h after surgery.