"nBackground: In the recent years, concerns have been raised about the incidence of reproductive disorders in human populations. The present study was aimed to determine the effects of maternal exposure to Di 2 ethylhexylphthalate (DEHP) on postnatal development of ovary in Wistar rat offsprings."n "nMethods: Forty female Wistar rats were randomly divided in four equal experiment groups; an oil vehicle group and three DEHP-treated groups that received 10, 100 and 500 mg/kg/day Di 2 ethylhexylphthalate by gavage during lactation, respectively. The ovaries of pups were removed at 60 days of postnatal development; their weights recorded and fixed in Bouin's solution; subsequently 6 µm serial paraffin sections were stained with haematoxylin-eosin; the structural changes of ovarian follicles and corpora lutea were studied."n "nResults: There was no significant difference on mean body weights of offsprings among different groups. However, the mean of ovary weight was decreased significantly (p= 0.037) in 500 mg/kg/day DEHP group. Significant decreases were seen in mean number of primary follicles (p= 0.012) and mean number and diameter of secondary (p= 0.023 and p= 0.012, respectively) and antral (p= 0.025 and p= 0.018, respectively) follicles in high dose DEHP-treated group compared to sham group. Also, mean number of corpora lutea decreased significantly (p= 0.023) at 60 days of age in ovary of offspring in 500 mg/kg/day DEHP group. Moreover, significant increases were seen in number of atretic follicles in moderate (p= 0.012) and high (p= 0.036) DEHP-treated groups."n "nConclusion: Present study showed that maternal exposure to Di 2 ethylhexylphthalate during lactation affects postnatal development of ovary in offspring Wistar rats and reduces their fertility and reproductive efficiency at puberty.