The feasibility of patient-controlled on-demand analgesia by the intramuscular route during labour was tested on 10 primigravid mothers. Pethidine 50 mg or meptazinol 75 mg was available double-blind at minimum intervals of 20 min. The mean dose demanded was 190 (SD 96.2) mg of pethidine and 285 (SD 97.8) mg of meptazinol. The dose of pethidine is similar to that demanded by the intravenous route. Pain evaluations were not significantly different, but one mother who had meptazinol opted for epidural analgesia, and 2 wished they had done so. The system could be easily managed by all the mothers and there were not technical difficulties. Self-administered intramuscular analgesia could be instituted by a midwife with a dosage scheme similar to current practice. A field trial by midwives of self-administered intramuscular analgesia with pethidine is indicated.