Abstract: Objective Transplantation of adipose-derived stem cells (ADSCs) is associated with potential risks of late complications including tumorigenesis due to the active proliferation of the cells. We aimed to test the effect of transplantation of ADSCs with suppressed proliferation by gamma irradiation in the treatment of thin endometrium in rats. Methods ADSCs were isolated from female SD rats and identified by detecting the surface antigens with flow cytometry. After exposure to gamma irradiation at 0, 5 Gy and 10 Gy, the cells were examined for changes in colony-forming ability. Twenty-four female rats with chemically induced thin endometrium were randomized into 4 equal groups and at 6–8 h after modeling, the rats received intrauterine injection of non-irradiated ADSCs (group I), 5 Gy irradiated ADSCs (group II), 10 Gy irradiated ADSCs (group III), or PBS only (group IV). Endometrial pathology was analyzed with HE staining in these rats in the third estrus phase following the cell transplantation. Results The ADSCs showed a complete loss of proliferative capacity after exposure to 10 Gy irradiation. After the cell transplantation, the endometrium thickness was thicker in group I and II than in group IV (P<0.01), but there was no significant difference between groups III and IV. Conclusions Gamma irradiation impairs the proliferative capacity of ADSCs in vitro. Exposure to 10 Gy irradiation causes a total loss of proliferation capacity of the ADSCs, which have no therapeutic potential; 5 Gy irradiation causes partial loss of proliferation capacity of the cells, which still retain the activity to promote endometrial cell regeneration.