High resolution autoradiography was used to study the basal pattern of glucose-utilization in the rat thalamus and hypothalamus. Rats were injected via chronic jugular catheter with (1-14C)-glucose and sacrificed 30 min later. The high resolution thaw-mount autoradiographic procedure, using 4 micron frozen sections and nuclear emulsion, permitted discrimination of regional variations in glucose-utilization that have not yet been described. Quantitative data were obtained by means of digital image analysis and computerized densitometry. In the thalamus, high activity was present in the anterodorsal, anteroventral, laterodorsal and reticular nuclei, while low activity was found in the mediodorsal and paraventricular nuclei. The autoradiographic pattern of glucose utilization in the thalamus corresponds largely to classical cytoarchitectonic subdivisions. In the hypothalamus, the median eminence, arcuate nucleus, and periventricular nucleus showed the lowest activity, whereas certain parts of the lateral hypothalamus appeared high. Very high activity was present in mammillary nuclei. The described detailed anatomical data of glucose-utilization may provide insights into the functional circuitry of thalamic and hypothalamic systems and serve as a baseline from which experimental manipulations can be assessed.