Premature ovarian insufficiency (POI), a fertility disorder affecting women under 40years of age, is characterized by early loss of ovarian function. This study was aimed to maintain ovarian function in POI animal models by mesenchymal stem cells (MSCs) transplantation with/without the supplementation of platelet-rich plasma (PRP). Adipose tissue-derived MSCs were isolated from inbred rats (Fisher-344), and constitutive expression of both VEGF and GFP were maintained by transfection with plasmids, pVEGF and pGFP-N. PRP was derived from the blood of healthy untreated rats. A total of 60 rats were divided into 5 groups of 12 rats in each. First group was kept as untreated-control (Control), and POI model was induced in Fisher-344 rats by cyclophosphamide in the next four groups. Second group was kept as sham-operated-control (Sham). MSC, PRP and MSC+ PRP-treated groups were transplanted following the validation of POI model in rats. After 2months following the transplantation, anti-mullerian-hormone (AMH) and oestradiol (E-2) blood levels were measured. Follicles were evaluated after hematoxylin-eosin staining, and the immunofluorescence staining and gene expression analyses were performed to show the ovarian regeneration. The follicular count was improved after MSC- and MSC+PRP-treatment to 63% of Control-group and significantly higher than that in Sham-group, but a significant increase was not observed in PRP-group. Higher AMH and E-2 levels were measured in MSC+PRP than in Sham-group, and CXCL12, BMP-4, TGF-beta and IGF-1 expressions were also increased. This study showed MSCs +/-PRP transplantation after POI supports recovery of the follicular count and function. For ovarian recovery, a single administration of PRP was found not sufficient. Although MSC treatment increased follicular regeneration, better results were obtained in the co-transplantation of MSCs and PRP. These results might be promising for follicular regeneration in POI patients.