A case of peritoneal papillary serous carcinoma arising in an infertile patient during ovulation-induction therapy is presented. A 34-year-old woman with past history of ovulation-induction therapy for infertility again received fertility drugs. During the use of gonadotropic hormones, massive ascites developed and an exploratory laparotomy revealed serous papillary carcinoma on the surface of bilateral ovaries, pelvic peritoneum, and omentum. Immunohistochemical analysis showed the tumor cells to be positive for luteinizing hormone/human chorionic gonadotropin receptors and negative for sex steroid receptors. A possible relationship between the use of gonadotropic hormones and cancer development is discussed.