We compared normal and vitiliginous areas and found: surface temperature was increased; sweat production was increased; bleeding time was prolonged and the quantity of bleeding was increased. In both normal and vitiliginous areas, responses to locally administered acetylcholine, epinephrine, and histamine were similar. These results suggest that there is enhanced cholinergic activity invitiliginous skin. This may be a direct effect of increased local acetylcholine concentration due either to increased secretion or delayed local clearing. On the other hand, this cholinergic activity may be due to relatively diminished locat epinephrine and l-norepineph-rine resulting from decreased secretion or a more rapid clearing of these sympathomimetic amines. The actual mechanism remains to be clarified.