As a first step to the evaluation of the functional significance of Staderini's nucleus intercalatus, electrophysiological experiments have been performed on rabbits, testing the hypothesis that neuronal elements of the nucleus intercalatus might react to gustatory stimuli. This possibility is suggested by topographical and hodological considerations. Foci of unitary or multiunitary neuronal activity were found in the nucleus by means of exploring extracellular tungsten microelectrodes (histological controls after the experiments). Their firing patterns and rates were assessed before and after topical application on the lingual taste buds (papillae circumvallatae or foliatae) of sucrose (0.5 - 1 M), quinine (0.01-0.02 M), NaCl(0.5-2 M), KCl (0.5 M) or HCl (0.01 M). As a rule, it was observed that such stimuli do modify the activity of the neuronal elements explored, either increasing (72 p. 100 of the observations) or decreasing (28 p. 100) their firing rates. Experiments of simultaneous recording from the nucleus intercalatus and from a typical central relay for gustatory afferents (nucleus tractisolitarii) showed that very similar temporal patterns characterize the responses of bothstructures.