The levels and the distribution of monoamines within the rat circumvallate papilla have been studied. Noradrenaline was found in the connective tissue underlying the taste buds, whereas serotonin was located in the basal area of the gustatory epithelium but not inside the taste buds. Following denervation, noradrenaline levels decreased and serotonin levels increased. These results suggest that both neurotransmitters may have some mutual interaction in modulating transmission at the papilla.