The repercussion of propylthiouracil (PTU) use postnatally on brain histology have not yet been intensely scrutinized. To examine whether Withania somnifera mitigate the structural effects of propylthiouracil on rat brain, rats were distributed into group A enrolled ten pups that were received -orally- distilled water (D.W) daily from postnatal day (PND) 3 to PND 43. Group B: enrolled pups (n=8) subjected to oral doses of PTU (1 mg/kg/day) from PND 3 to PND 25. Then they were gavaged with D.W till PND 43. Group C: included pups (n=8) that were subjected orally to PTU (1mg/kg/day) PND 3 to PND 25 with receiving levothyroxine (four microgram /100g/day) from PND 25 to PND 43. Group D included pups (n=8) that were treated with oral PTU 1 mg/kg/day PND 3 to PND 25 with receiving Withania somnifera extract (200 mg/kg/day) from PND 25 to PND 43. Cerebellar sections of rats of group B exhibited disorganization of the cerebellar cortex with a falling off in the Purkinje cells' count and the appearance of degenerated cells. Hippocampal sections (of rats of group B) proclaimed a falling off in the breadth of the pyramidal zone of cornu Amonis. Sections of the cerebral cortex of rats in group B exhibited the presence of large degenerated neurons. Sections of rats' brains belonging to groups C and D showed improved cerebellar and cerebral cortex and hippocampal and cerebral cortical segments. Levothyroxine and Withania somnifera mitigates the structural changes in the peripubertal rat brain induced by postnatal PTU administration.