SUMMARY In a randomized double-blind study the effect of the addition of adrenaline to extradural dia-morphine was assessed in 54 patients after Caesarean section. Patients received extradural diamorphine 5 mg in saline 10 ml with or without adrenaline 1 in 200 000 for postoperative pain relief. Analgesia was profound and of rapid onset in both groups. Duration of analgesia was greater in the adrenaline group (time to next analgesia 12.51 ± 0.94 h, mean ± SEM), than in the saline group (9.87 ± 0.98 h) (P = 0.057). Analgesia was also more consistent in the adrenaline group, with 77% of patients having more than 8 h of good analgesia compared with 48% in the saline group (P