Background & aim: Cyclophosphamide, an alkylating agent used in the treatment of cancer that has many side effects on different organs, including the gonads .The purpose of this study was to investigate the effects of an antioxidant Ellagic acid on cyclophosphamide -induced toxicity in rat fetal ovarian tissue. Methods: Forty two pregnant  female Wistar rats weighing 250-200 gr were randomly divided into seven groups.The first, second, third, fourth, fifth and sixth 5 mg/ kg cyclophosphamide on days 1, 13 and 18 were given intraperitoneal remote pregnancy .The fourth, fifth and sixth groups hour after receiving cyclophosphamide, Ellagic acid (10 mg/kg) has received in the course of pregnancy.Control groups and seven group (normal) during pregnancy daily orally received 0.5 mL of saline. After postpartum, Neonatal rats were anesthetized with ether. Animals were dissects, then Ovaries were removed and transferred to 10% formalin solution. After tissue processing, tissue sections were prepared and H&E stained.Data were analyzed by SPSSsoftware and One- way ANOVA test. Results: The groups that were exposed to cyclophosphamide ovarian mean of diameter, primordial follicle diameter and number of follicular cell of primordialin control group compared to ellagic acid treatments showed a significant decrease. Conclusion: The results showed that Ellagic acid due to its antioxidant properties could reduce the harmful effects caused by cyclophosphamide in the fetal ovary.