We conducted a prospective, randomised, double-blind trial to study the effect of Synacthen Depot in 18 parturients with postdural puncture headache following deliberate or accidental dural puncture. Women were randomly allocated to receive either Synacthen Depot 1 mg (1 ml) or 0.9% saline 1 ml intramuscularly. Using a 10-cm visual analogue scale, severity of headache was measured before and at intervals until 48 h after injection. There was no difference in the severity of headache or requirement for epidural blood patch. We conclude that there is no advantage to the use of Synacthen Depot 1 mg for the treatment of postdural puncture headache.