Studies have been made of the effect of exogeneous serotonin on responses of taste receptors recorded from the hypoglossal nerve during adequate stimulation. It was shown that serotonin evokes afferent discharge in this nerve and significantly increases responses of taste receptors. Stimulating effect of serotonin appears 15-20 min after its application and gradually develops reaching maximum within 60 min after injection. Competitive antagonist of serotonin, 7-methyltryptamine, inhibits taste afferent responses and blocks stimulating effect of serotonin. Possible role of serotoninergic mechanism in afferent impulse activity of the taste receptive apparatus is discussed.