Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of ovulation induction with exogenous gonadotropins, such as human menopausal gonadotropin and follicle-stimulating hormone. These hormones are considered to increase capillary permeability and cause third space fluid shift. We report an autopsy case of severe OHSS in a 28-year-old Japanese female. The patient developed bilateral chest pain and progressive dyspnea during the course of administration of human gonadotropins. Pleural effusion and hypouresis clinically disappeared 4 days after the onset of the symptoms, but the patient died suddenly of rapid respiratory insufficiency. Autopsy examination revealed massive pulmonary edema, intra-alveolar hemorrhage and pleural effusion without any evidence of pulmonary thromboembolism. Histopathological examination of the ovary demonstrated multiple well-developed follicle formations, consistent with OHSS. It is very important to recognize that massive pulmonary edema can occur in a patient with OHSS. To the best of our knowledge, this is the first autopsy report of a patient with severe OHSS.