Background: Increased levels of kisspeptin are associated with hypothalamus-pituitary- ovary axis dysfunction. It may lead to the development of polycystic ovary syndrome (PCOS). Objective: We aimed to investigate the effect of prenatal kisspeptin antagonist exposure on the development of PCOS in prenatally androgenized rats in adulthood. Materials and Methods: In this experimental study, pregnant rats were injected with free testosterone (T, 5 mg/day) or T+P271 (kisspeptin antagonist) on the 20th day of the pregnancy period (n = 5 in each group), while rats in the control group received solvent. Female offspring were examined in terms of anogenital distance (AGD), anovaginal distance (AVD), vaginal opening, serum total testosterone (TT) levels, ovarian follicles, and the regularity of estrous cycles in adulthood. AGD and AVD were measured using a vernier caliper. TT levels were measured using the enzyme-linked immunosorbent assay method. Ovaries were fixed in 10% formalin, tissue processing was done by a standard protocol, and then ovaries embedded in paraffin. 5 μmthickness ovarian sections mounted on a glass slide, deparaffinized, and stained using Harris’s Hematoxylin and Eosin Y. Results: AGD, AVD (p < 0.001), TT levels (p = 0.02), and the numbers of preantral and antral follicles (p < 0.001) in the ovaries were significantly decreased in prenatally TP271- exposed rats compared to prenatally T-exposed rats. The age of vaginal opening was early in T-P271-exposed rats compared to prenatally T-exposed rats (p < 0.001). The number of corpora lutea was significantly increased in T-P271-exposed rats (p < 0.001). No cystic follicles were observed in the ovaries of prenatally T-P271-exposed rats. Prenatally T-P271-exposed rats had regular estrous cycles compared to prenatally T-exposed rats. Conclusion: Prenatal exposure to kisspeptin antagonist can prevent PCOS development in prenatally androgenized rats in adulthood. Key words: Androgen, Kisspeptin antagonist, Polycystic ovary syndrome, Rat.