In view of recent theories suggesting a role for basal ganglia circuits in motor control and cognition, rats with bilateral electrolytic lesions of the lateral part of the globus pallidus were compared with control rats on motor coordination tasks and spatial learning in the Morris water maze. By comparison with sham-operated controls, rats with lesions of the lateral pallidum were impaired during acquisition of the rotorod task. Deficits were observed in a wooden beam task, but not in hole-board and suspended string tests. In addition, lesioned rats were impaired during acquisition of place learning but not of visuomotor guidance in the Morris water maze. Alterations of brain metabolism, as assessed by cytochrome oxidase activity, were found in three regions of lesioned rats, the subthalamic nucleus, the superior colliculus, and the centromedial thalamus of lesioned rats, probably as a result of interrupted neocortico-basal ganglia circuitry as a secondary consequence of the primary lesion.