A double-blind trial of dihydroergotamine (DHE) nasal spray compared with placebo was carried out in patients with cluster headache. Twenty-five patients were included in the trial. In three patients, all receiving DHE, the pain attacks ceased after five attacks. In the other 22 patients, 133 attacks were treated with placebo and 137 attacks with DHE nasal spray (dosage, 1 mg of DHE). The trial showed that the treatment given has no effect on the attack frequency or the duration of the single attack. However, the treatment had a significant effect on the intensity of the single attacks. It can be concluded that the trial should be repeated, using a larger dosage of DHE. This should be ethically justifiable, since none of the patients had any adverse reactions locally in the mucous membrane of the nose or systemically.