This study was carried out to investigate whether repeated controlled ovarian hyperstimulation (COH) affects ovarian reserve. For this reason, we aimed to show possible changes in the expression of PTEN and FOXO3, which are involved in preserving the over-reserve, after applying the COH protocol methods. For this purpose, 18 young Wistar albino female rats (8 weeks old) were randomly assigned as Group-1(control), Group-2 and Group-3 as 6 subjects in each group. Experimental groups were treated with 10 IU/0.1ml PMSG and a COH protocol consisting of 10 IU/0.1ml hCG injection after 48 hours. This procedure was applied 3 and 5 times to Group-2 and Group-3 respectively. For the control groups, the same procedures were performed with 0.1 ml of 0.9% NaCl solution. At the end of the experiment, the ovarium tissues were placed in 10% neutral formaldehyde solution for light microscopic examinations. In histological sections stained with H-E, the number of ovarian follicles was determined using the physical dissector method. However, the expression of PTEN, FOXO3, and LH-R molecules was evaluated by IHC methods. As a result of our study, it was concluded that COH administration reduces the expression levels number of PTEN and FOXO3 proteins and LH-R, which are among the essential components of the PIK3 intracellular signaling pathway and also increased the levels of hormones such as FSH, E2 and LH, which are over-reserve markers, and causes adverse effects on the histological structure, oocyte morphology and number of ovaries.