The rate of local cerebral glucose utilization was determined for quantification of energy metabolism in macrostructures of the sensorimotor system during propagation of focal motor seizures in 24-month-old monkeys. The rate was measured in 4 control animals and in 4 monkeys each with seizures limited to the contralateral face, seizures of the contralateral face and upper extremity, and bilateral expression of seizures. Glucose utilization increased significantly, primarily unilaterally, with propagation. The increase was greatest in the sensory and motor cerebral cortices, putamen, and globus pallidus, was somewhat less in sensory and motor thalamic relay nuclei, and was least in the cerebellar cortex.