Background: Infertility is one of the common problems among couples, affecting millions of people worldwide. Polycystic ovary syndrome(PCOS) is one of the main causes of infertility in women and is associated with abnormal folliculogenesis, angiogenesis and fibrosis. Common treatments may lead to numerous adverse effects on the patient's quality of life. The present study aimed to investigate the effects of human menstrual blood-derived stem cells on the ovarian histology of a PCOS model of Wistar rats. Results: Based on the Papanicolaou test and H&E staining results, the number of primordial, primary, secondary, and antral follicles in the PCOS and PCOS-Sham groups increased significantly compared to the control, while they were significantly decreased in the PCOS+Stem cells group compared to the PCOS and PCOS-Sham groups. Further, the number of atretic follicles in both PCOS and PCOS-Sham groups significantly was increased in comparison with the control group, and was decreased in the PCOS+Stem cells group compared to the two mentioned groups. Moreover, graafian folioles reduction in PCOS and PCOS-Sham groups and increase in PCOS+Stem cells group was significant. Based on the Mason's trichrome data, the number of blood vessels in PCOS and PCOS-Sham groups was increased significantly compared to the control group and decreased in PCOS+Stem cells group related to PCOS and PCOS-Sham groups. Conclusion: The administration of MenSCs improved folliculogenesis in rat polycystic ovaries. Also, MenSCs could ameliorate the PCOS symptoms by improving fibrosis as well as angiogenesis and weight gain.