Since in migraineurs a change in dopaminergic tone has been hypothesized and since in man prolactin secretionby the lactotroph cells is controlled by hypothalamic inhibitory factors (of which dopamine is the best known), wedecided to investigate plasma prolactin (PRL) response to L-Dopa in a group of migraineurs.We tested 5 women suffering from common migraine and 5 healthy women as controls.A different behaviour of PRL secretion was observed in the two groups. In migraineurs the inhibition of PRLsecretion was less marked than in normals, with a statistically significant difference at 30 and 60 minutes.This difference might suggest a reduced responsiveness of the pituitary lactotroph cells to the action ofdopaminergic agents. The mechanisms accounting for this peculiar behaviour of PRL secretion in migraineurs arestill to be elucidated.