The purpose of this study was to investigate the effect of kisspeptin-54 on ovarian morphology and vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), protein kinase A (PKA) and protein kinase C (PKC) levels in an ovarian hyperstimulation syndrome (OHSS) rat model, which is a possible complication of controlled ovarian hyperstimulation. For this purpose, immature female Sprague-Dawley rats (25days old, 30-40g) were randomly divided into five groups (control, sham, OHSS model, short-term kisspeptin-54 administered OHSS model and long-term kisspeptin-54 administered OHSS model). Serum LH and FSH levels were determined by enzyme-linked immunosorbent assay. Immunohistochemistry and quantitative RT-PCR were performed for VEGF, PEDF, PKA and PKC in ovaries and granulosa cells, respectively. It was observed that there was dilatation in fallopian tubes and an abnormal increase in ovarian weight and volume in the OHSS group, and these morphologies decreased with kisspeptin-54 treatment. After the administration of kisspeptin-54 in the OHSS group, VEGF, PKA and PKC levels reduced and PEDF levels increased in both mRNA and protein levels. It was determined that in the OHSS model, VEGF increased as PEDF decreased, and kisspeptin-54 reduced the effects of OHSS. It was determined that long-term kisspeptin-54 treatment was more effective than short-term administration. It is considered that kisspeptin-54 is an agent that protects ovarian reserve and oocyte maturation in women at risk of OHSS.