Long-Evans hooded rat pups were given 600 mg/kg body weight lead acetate every 24 hours via stomach intubation beginning one day after birth until an accumulative dose of 2400 mg/kg was administered. The body weights of the lead treated rat pups at 10 and 30 days of age were not significantly decreased when compared to controls. The brain weights at 10 and 30 days of age in the lead exposed rats was significantly greater than those of the control rats. Blood lead levels averaged 526.35 micrograms/dl at 10 days of age in lead treated rats and 0.079 microgram/dl in controls. Quantitative histological examination and Golgi analysis of the cerebellum revealed a number of alterations in the lead treated rats. Lead exposure resulted in a significant decrease in the molecular layer width (72%). The granule cell density was depressed in the lead exposed rats, despite the observation that the granule cell layer width did not differ significantly in the two groups. This suggests that the granule cell packing in this layer was decreased. The Golgi study revealed a reduction in the dendritic arborization of these cells in the treated rats at 30 days of age. There was a 20% reduction in height and a 14% reduction in width in the Purkinje cells dendrites of the lead exposed rats when compared to Purkinje cells of age matched controls. Estimation of the amount of dendritic material by the Scholl method revealed a 40% decrease in the dendritic arborization of Purkinje cells following lead exposure.