Migraine frequently induces hypotension, which has a large postural component. Since pain and other symptoms of the migraine syndrome have been suggested to be central in nature, an involvement of the dopaminergic pathways within the central nervous system that mediate hypotensive responses, might be postulated in migraine patients. In the study, a test dose (2.5 mg) of bromocriptine, a brain dopamine agonist, induced an intense hypotensive reaction in migraineurs, but not in controls. During bromocriptine-induced hypotension, serum dopamine β-hydroxylase activity did not change. The fall of blood pressure, due to bromocriptine, in migraine patients could be considered as an indirect expression of brain dopamine receptor supersensitivity caused by a deficiency of dopamine and or endogenous morphine-like substances. This mechanism is compatible with the hypothesis which considers migraine as a clinical condition of chronic natural opioid abstinence.