Lumbar epidural anaesthesia was used as an anticonvulsant in a series of 1 106 patients with hypertension in labour, including 7 patients with eclampsia. Six of the 1 074 patients in whom epidural analgesia was successful subsequently had convulsions. Of these 4 had convulsions after delivery, which took place at least 2 1/2 hours after the last dose of local anaesthetic, and the 2 others within 5 minutes of receiving the first dose of bupivacaine. We conclude that before it wears off epidural anaesthesia is an effective way of preventing eclampsia and that other anticonvulsant therapy is not required, although the latter may be necessary before the procedure. The possible mechanism of the anticonvulsant action is discussed.