A 50-year-old woman was admitted to our hospital because of abdominal distension and fullness. Computed tomography and magnetic resonance imaging showed bilateral ovarian tumors. Although these ovarian tumors were suspected of being metastatic, the primary tumor site could not be detected before the bilateral salpingo-oophorectomy. At the time of laparotomy, there was no apparent peritoneal dissemination or ascites. The pathological findings suggested that the ovarian tumors were metastases from cancer of the digestive tract. Positron emission tomography using (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) and double-balloon enteroscopy detected jejunal cancer. A second laparotomy for the resection of jejunal cancer was performed. The patient received adjuvant chemotherapy, and there has not been any recurrence for 24 months since the resection was performed. In conclusion, FDG-PET was found to play a valuable role in the detection of the primary tumor. Intensive chemotherapy and surgical treatment also contributed to the long-term survival of the patient.