In a controlled trial epidural buprenorphine was compared with epidural morphine as the sole means of analgesia after major abdominal surgery. Bolus injections of buprenorphine 60 micrograms in 10 ml or morphine 2 mg in 10 ml of normal saline were given on demand for the first 48 hours postoperatively. Both drugs produced significant reduction in pain scores as assessed by the linear visual analogue scale and both produced prolonged analgesia at this dosage, which could be extended by further 'top-ups'. The authors conclude that, for postoperative epidural analgesia, buprenorphine may be the opiate of choice and the reasons for this are discussed.