Lurcher mutant mice, characterized by degeneration of cerebellar granule and Purkinje cells, were compared to normal littermate controls in a rotorod test, consisting of a wheel turning at constant speed which required on the part of the animal postural adjustments in order to maintain equilibrium. Identical baseline rates for the two groups were assured by changing the speed and size of the rotating rod. Although both groups were able to learn the task, the fall latencies of normal mice exceeded those of lurchers. These results indicate that cerebellar cortical atrophy does not abolish this form of sensorimotor learning. However, brain-damaged animals are unable to reach the same level of performance as normal animals. In contrast to the results in lurcher mutants, no sensorimotor learning was displayed by hot-foot mutants and staggerer mutants.