In order to detect the ability of epidural morphine, administered by the caudal route, to produce pain relief and in order to compare pain relief by this method with intramuscular injections of opiates, 90 patients scheduled for surgery below the umbilical level were studied. Four milligrams of preservative-free morphine in 10 ml normal saline was compared with intramuscular injections of opiates, using a visual analogue scale. The average pain score was significantly lower in the epidural group during the first 12 postoperative hours. In the epidural group, 38% required additional intramuscular injections during the first 12 h, whereas 86% of the patients in the intramuscular group received opiate injections. No patients developed respiratory depression. Side effects were more common in the intramuscular group than in the epidural group. It is concluded that epidural morphine by the caudal route is a better choice than intramuscular injections in controlling postoperative pain below the umbilical level.