Efficacy with currently marketed antimigraine compounds is less than optimal. 311C90 is a novel and selective 5-HT1D receptor agonist in development for the acute treatment of migraine. It shows evidence of both central and peripheral activity within the trigemino-vascular system and it is rapidly absorbed following oral administration. In clinical studies in migraine patients, a headache response at 2 hours has been observed in 65–81% of patients at doses above 1 mg. Favourable response rates are reported as early as 1 hour post-dose and efficacy rates continue to improve up to 4 hours. Headache recurrence is reported by 25-35% of patients and 311C90 is also effective in relieving the non-headache symptoms of migrain