In general, mammalian taste neurons are broadly responsive to stimuli representing different taste qualities. In the hamster, this breadth of tuning increases systematically from peripheral to successively higher brain stem neurons. Some investigators have classified taste-responsive neurons into best-stimulus categories on the basis of which of the 4 basic basic stimuli (sucrose, NaCl, HCl, or quinine hydrochloride) elicits the maximum response. Attempts by others to demonstrate the existence of taste neuron types in the chorda tympani nerve and medulla of the rat using hierarchical cluster analysis have not been successful, resulting in the conclusion that there are no neuron types in the rat gustatory system. The present study was designed to look at the question of neuron types in the hamster, a species with a broader range of gustatory sensitivities to anterior tongue stimulation. Responses of 30 neurons in the nucleus tractus solitarius (NTS) and 31 neurons in the parabrachial nuclei (PbN) of the hamster to an array of 18 stimulus compounds were recorded extracellularly. The similarities of the neural response profiles of these cells at each synaptic level were compared using multivariate statistical techniques. The possible grouping of cells on the basis of similarities in their response functions was examined with hierarchical cluster analysis, and the relationships among these response functions were examined with multidimensional scaling. The results of the cluster analysis suggested that at both the NTS and PbN, there are 3 clusters of neural response profiles. These 3 clusters of response profiles are characterized at both synaptic levels by their predominant sensitivity to sucrose and other sweet-tasting compounds, sodium salts, and nonsodium salts and acids. Representation of these neurons in a 2-dimensional space yielded 3 nonoverlapping groups of cells in both the NTS and PbN, corresponding to the 3 groups identified by the hierarchical cluster solution.