This study was undertaken to elucidate the quantitative synaptic changes on the dendritic spines of the Purkinje cells of the rats born from streptozotocin-induced diabetic mothers. The brains of the experimental rats including cerebellum decreased in weight and in size on days 1, 30 and 70 as compared to those of the age-matched controls. Ultrastructural observation did not show any significant destructive changes in their cerebellum on days 30 and 70. However, the measurements for the synaptic length and area of dendritic spine of their Purkinje cells on days 30 and 70 showed an increase of about 10% in the former and of about 42% in the latter as compared to those in the age-matched control. These evidences suggest a presence of compensation in the brains thus damaged.