The rate of gastric emptying was studied in 30 women during labour. All the women had received pethidine 100 mg i.m. for analgesia and, subsequently, extradural analgesia had been established for obstetric indications. The women were allocated randomly to two groups: 15 received naloxone 1.2 mg i.v. and 15 were given saline 3 ml (placebo). All 30 patients were then given paracetamol 1.5 g orally with water 100 ml. The amount of paracetamol absorbed, and hence gastric emptying, was significantly greater in the naloxone group in the first 30 min following the administration of the paracetamol.