Background: Cyclophosphamide (CLP), used as an anticancer therapy , One of its side effects in women is through inducing ovarian toxicity and consequently infertility Aim of work: to evaluate the impact of BM-MSCs&AT-MSCs in the overcome of cyclophosphamide-induced ovarian damage in rats. Materials&Methods: Forty female adult Albino rats were randomly divided into four groups. Group I (control group). Group II (cyclophosphamide treated group) were subjected to intra-peritoneal injection of 150 mg/kg- B.W, followed by a dose of 8 mg/kg every week, the rats were scarified after 3 weeks. Group III (BM-MSCs treated group) were treated by cyclophosphamide in the same manner as in group II and after five weeks from the second CLP injection 100 μl of BM-MSCs mixture (2.5x106cells) in 100 μl PBS was injected intra-venous. Group IV(AT-MSCs treated group) were treated by CLP as in group II and after 5 weeks from the second CP injection, 100 μl of AT-MSCs mixture (2.5x106cells) in 100μl PBS was injected intra-venous, Then 30 days after cell therapy the rats were scarified, Ovarian sample sections were stained with different stains, H& , M on T ic o e n Immunohistochemical stains for anti-PCNA antibody. The average number of primordial germ follicles, % of collagen fibers, area % of +ve immune-reactivity area for PCNA were determined by histomorphometric tests and analyzed statistically. Results: Histological examination of the ovaries of CLP treated group revealed severe degeneration of ovarian follicles with sloughing of granulosa cells. The ovarian follicles treated with BM-MSCs showed a normal appearance of oogenesis in comparison to the cyclophosphamide-group. The AT-MSCs treated group rats showed relative improvement of oogenesis but no graafian follicle was detected. Conclusion: BM-MSCs and AT-MSCs were impressive in the therapy of ovarian failure in albino rat model where they repair the ovarian structure and protected ovary against CLP-induced toxicity. However BM-MSCs more effective [Talaat M. Mohamed, Gamal Elsayed Abd-Salam, Kamal M. Kamal, Eman El Bana, Mohammed A. Gebba.Comparative Study of Bone Marrow and Adipose Tissue-Mesenchymal Stem Cells in The Treatment of Cyclophosphamide Induced Ovarian Damage In Adult Female Albino rats. Nat Sci2019;17(12):267-283]. ISSN 1545-0740 (print); ISSN 2375-7167 (online).http://www.sciencepub.net/nature. 33. doi:10.7537/marsnsj171219.33.