Progression of episodic migraine to chronic migraine may be related to comorbid medical conditions. In this study, we focused on the role played by arterial hypertension in migraine transformation. Several studies reveal that hypertension is associated with chronic migraine and may induce migraine chronification. Hypertension probably amplifies the effects of migraine on the vascular wall further enhancing the endothelial dysfunction in cerebral vasculature. Consequently, monitoring of blood pressure is recommended in migraineurs showing an otherwise unexplained increase in attack frequency. Studies are needed to verify if prophylactic treatment with drugs improving endothelial function (e.g. calcium channel blockers, beta blockers, calcium inhibitors, ACE inhibitors and sartans) may selectively ameliorate the course of migraine in these patients.