Sumatriptan, a selective 5-hydroxytryptamine (5HT1D)-receptor agonist, has recently been introduced in the pharmacotherapy of acute migrane attacks. The potential vasoactive effect of sumatriptan on human dural vessels in vivo, however, is still a matter of controversy. We investigated the effects of sumatriptan on dural vessels after subcutaneous or intra-arterial injection. During interventional angiography, the middle meningeal artery (MMA) of nine patients was catheterized with a microcatheter using the transfemoral route. Three MMA were entirely normal, two supplied a dural arteriovenous fistula (AVF) and four were transdural feeders to a brain arteriovenous malformation (AVM). Sumatriptan was injected either into the subcutaneous tissue of the right shoulder (6 mg, two patients) or into the catheterized MMA (2 mg, six patients). The substance caused a marked vasoconstriction of the three normal MMA, visible angiographically and confirmed by intravascular Doppler ultrasonography. Vasoconstriction was still present in the last angiogram obtained 15 min post-injection. Slightly hypertrophied feeders to dural AVF and to brain AVM showed some vasoconstriction in one and four patients, respectively. In two patients with markedly hypertrophied dural feeders to a dural AVF and to a brain AVM, respectively, rapid shunting probably prevented obvious vasoactive effects of sumatriptan. The data obtained by angiography and intravascular Doppler ultrasonography provide strong evidence that sumatriptan has a vasoconstrictive effect on normal as well as hypertrophied dural vessels.