This cross-over, double blind, randomized, multicentre study evaluated the consistency of efficacy and safety of oral sumatriptan in 233 migraneurs. The patients received 50 mg oral sumatriptan or placebo for the treatment of 12 migraine attacks. Within each group of 4 attacks, three were treated with sumatriptan and one with placebo, according to a randomization list. Over all the attacks, the efficacy rate was statistically significant for sumatriptan against placebo at 2 or 4 hours (2 hours: sumatriptan 60%, PLO 38%, p < 0.001; 4 hours sumatriptan 79%, PLO 47%, p < 0.001). Oral sumatriptan was similarly effective at relieving the associated symptoms and at reducing clinical disability in most attacks. The incidence of adverse events did not differ between treatment groups. All the events recorded were mild to moderate as intensity and resolved spontaneously.