In a prospective, double-blind, randomised controlled trial, we compared the efficacy of patient-controlled analgesia using remifentanil (25-30 μg per bolus) with intramuscular pethidine (50-75 mg) for labour analgesia in 69 parturients. Parturients receiving patient-controlled analgesia reported less pain than those receiving intramuscular pethidine throughout the study period (p < 0.001), with maximal reduction in visual analogue pain score at 2 h after commencement of analgesia (mean (SD) 20 (17) in the patient-controlled analgesia group and 36 (22) in the intramuscular pethidine group. The median (95% CI) time to the first request for rescue analgesics was significantly longer with patient-controlled analgesia (8.0 (6.8-9.2) h) compared with intramuscular pethidine (4.9 (3.8-5.4) h, p < 0.001). Maternal satisfaction scores were also higher with remifentanil compared with intramuscular pethidine (p= 0.001). There was no report of sedation, aponea or oxygen desaturation in either group, and Apgar scores were similar between groups. We conclude that patient-controlled analgesia with remifentanil provides better labour analgesia and maternal satisfaction than intramuscular pethidine. At this dose, maternal and fetal side effects were uncommon.