Inappropriate activation of the trigemino-vascular system is thought to be important in the pathogenesis of a migraine attack. The 5-HTID agonist sumatriptan, which is highly effective in the acute treatment of migraine, inhibits trigemino-vascular activation in animals, although its actions are normally limited to peripheral components of the trigemino-vascular system. 311C90, a novel 5-HTID agonist drug, which is also highly effective in the acute treatment of migraine, acts not only at these sites, but, additionally within the brainstem, inhibiting trigemino-vascular activation centrally as well as peripherally. This article describes the pre-clinical development of 311C90 and considers, specifically, the approaches taken in the design of a molecule with attributes which facilitate access to brainstem components of the trigeminal pathway and combine this with good oral bioavailability.