This double-blind, placebo-controlled, multicenter, parallel-group study assessed whether subcutaneous sumatriptan administered during the migraine aura would prolong or modify the aura and prevent or delay development of the headache. One hundred seventy-one patients (88 receiving 6 mg sumatriptan, 83 receiving placebo) treated a single attack of migraine with typical aura at home, by self-injection. The median duration of aura following the first injection was 25 minutes for the sumatriptan group and 30 minutes for the placebo group (NS). The aura symptom profile was similar for the two treatment groups. The proportion of patients who developed a moderate or severe headache within 6 hours after dose administration was similar in the two groups--68% among those receiving sumatriptan and 75% among those receiving placebo (NS). Sumatriptan given during the aura did not prolong or alter the nature of the migraine aura and did not prevent or significantly delay headache development.