We evaluated the clinical significance of 18F-FDG PET to detect malignant ovarian neoplasms and tumor spread. 40 patients (median age: 57.5 years) underwent laparotomy because of clinical suspicion of malignant ovarian tumors or recurrent disease. The results of the preoperatively performed PET were correlated with the postoperative histologic diagnosis and the intraoperatively assessed tumor spread. In 10 of 40 patients benign tumors were found, among which a tubo-ovarian abscess was the only one diagnosed as false positive. 4/30 malignant neoplasms did not originate from the coelomic epithelium, but all were correctly recognized as malignant tumors by PET, as was recurrent ovarian cancer in 12 patients. Out of 14 primary ovarian carcinomas, 2 borderline tumors and 1 well-differentiated adenocarcinoma FIGO stage I were not correctly identified. Considering the tumor type, sensitivity, and specificity were 90%, calculating for the positive and negative predictive value 96% and 75%, respectively, and 90% for the diagnostic accuracy. Those statistical parameters were slightly lower for PET detection of lymph node metastasis and peritoneal carcinomatosis. Although its diagnostic accuracy may vary depending on the clinical application, 18F-FDG PET is basically a suitable method for detecting ovarian malignancies, particularly in patients with relapsed ovarian carcinoma.