A parenteral formulation of dihydroergotamine (DHE) is the only galenical form now available for the treatment of acute attacks of migraine in which a rapid onset of action is required. A recently developed nasal spray of DHE has been compared with intramuscular DHE for its venoconstrictor activity. In a randomised double-blind, cross-over trial, 9 healthy male volunteers received a single dose of DHE 1 mg intranasally, DHE 0.5 mg i.m. or placebo (intranasally and i.m.) on three different occasions, with an interval of at least 1 week between doses. Both active treatments, but not placebo, produced marked venoconstriction as shown by reduced compliance of superficial hand veins. The effect persisted for more than 8 h. The maximum venoconstrictor effect of 1 mg DHE intransally was 40±12% (mean ± SEM) and after 0.5 mg i.m. it was 52±15%. The time course of the venoconstrictor effect was similar after both routes of administration. Blood pressure and heart rate changes in these normotensive subjects were almost identical after dihydroergotamine and placebo. The results suggest that the nasal spray could be used as an alternative to parenteral DHE, permitting self-administration of the drug for the treatment of acute attacks of migraine.