Objectives. To investigate whether acupuncture is superior to placebo and equivalent to sumatriptan for the early treatment of an acute migraine attack. Design. Randomized, partly double-blind (sumatriptan versus placebo) trial. Setting. Two hospitals in Germany (one specialized in traditional Chinese medicine and one in the treatment of headache). Subjects. A total of 179 migraineurs experiencing the first symptoms of a developing migraine attack. Interventions. Traditional Chinese acupuncture, sumatriptan (6 mg subcutaneously) or placebo injection. Main outcome measure. Number of patients in whom a full migraine attack (defined as severe migraine headache) within 48 h was prevented. In patients who developed a migraine attack in spite of early treatment, acupuncture and sumatriptan were applied a second time, whilst patients initially randomized to placebo received sumatriptan. Results. A full migraine attack was prevented in 21 of 60 (35%) patients receiving acupuncture, 21 of 58 (36%) patients receiving sumatriptan and 11 of 61 (18%) patients receiving placebo (relative risk of having a full attack 0.79 (95% CI, 0.64-0.99) for acupuncture versus placebo, and 0.78 (95% CI, 0.62-0.98) for sumatriptan versus placebo). Response to the second intervention in patients who developed a full attack was better with sumatriptan (17/31 patients who received sumatriptan twice and 37/46 patients who had had placebo first) than with acupuncture (4/31). The number of patients reporting side-effects was 14 in the acupuncture group, 23 in the sumatriptan group and 10 in the placebo group. Conclusions. In this trial acupuncture and sumatriptan were more effective than a placebo injection in the early treatment of an acute migraine attack. When an attack could not be prevented, sumatriptan was more effective than acupuncture at relieving headache.