This paper deals with the possible significance that single neurons, which respond to local or remote temperature stimuli, may have in thermoregulatory control. Recordings of single neurons that appear to be involved in temperature regulation are easy to interpret as long as a functional association can be demonstrated. The processing of afferent thermal signals at different levels of the neuraxis exhibits differences in degree, depending on the location of the receptive field. Descending control of afferent temperature signals is already apparent at the segmental level of the spinal cord. It seems promising to search for central primary thermodetectors in the spinal cord rather than in those regions of the central nervous system where the principles of structural organization are largely unknown. In the hypothalamus, it is difficult to correlate neuronal responses to temperature with regulatory output, even in conscious animals. Characterization of thermoresponsive neurons by their sensitivity to biogenic amines might be used to establish a functional association. In vitro recordings from temperature-responsive neurons in the hypothalamus of rats and ducks indicate that a differentiation of intrinsic and synaptically induced thermosensitivity per se is not relevant to functional characterization.