The 2-deoxy-D-[14C]-glucose method for the quantitative determination of local cerebral glucose utilization has been applied to the mouse. The experiments were conducted in awake freely moving animals. Local cerebral glucose utilization was found to vary widely throughout the brain with the lowest values in white matter and the highest in gray matter. The most metabolically active structures were those involved in auditory function or in general motor activity. All the values were lower than those observed previously in the conscious rat. The use of free-moving animals may be of importance since it allows the study of physiological or pathological behavioral states.