Flushing in rosacea has been investigated by means of (a) pharmacological inhibition of some possible chemical mediators and (b) titration of bradykinin as a possible effector directly in the blood. Clonidine-inhibited flushing was seen in all patients (mean 45%), other drugs had poorer results. Bradykinin increased in all patients at the climax of flushing (mean 60%). These findings support the hypothesis that epinephrine promotes a bradykinin release responsible for vasodilation.