Abstract: A total of 200 rat pups starting from the first week after birth until the fifth week were used to investigate the effects of prenatal exposure to aspirin at doses of 12.5, 25 and 37.5 mg kg-1 on the postnatal development of brain parts. Cerebrum and cerebellum length and width were measured in addition to brain and body weights and allometric relationships between these parameters were calculated. The results indicated that all relationships were allometric with noticeable differences between all aspirin treated groups and the control group. These differences indicate that aspirin has an effect on the development of the examined brain parts mainly on the cerebellum length and width.