The aims of the present study were to determine the serum concentrations of insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-3 (IGFBP-3) and leptin and insulin resistance in benign and malignant epithelial ovarian tumors, and to discuss the use of these markers in benign-malignant tumor differentiation.Forty-seven postmenopausal women with ovarian tumor and 31 age-matched, postmenopausal, healthy controls were included in this study. Insulin resistance index by homeostasis model assessment (HOMA score) and fasting blood glucose (FBG), serum IGF-I, IGFBP-3, leptin and CA-125 concentrations were determined in all patients preoperatively. The results were evaluated according to postoperative histopathology results.According to postoperative histopathology results, the patients were divided into malignant (n = 23), benign (n = 24) and control (n = 31) groups. There were no differences among the groups in relation to age, body mass index, FBG and HOMA score (p > 0.05). Serum concentrations of CA-125 were elevated in the malignant group compared with the benign ovarian tumor and control groups (p 0.05).Serum leptin and HOMA score have not been found to be valid indicators in ovarian tumors. However, the present data suggest that low concentrations of IGF-I and IGFBP-3 could be a reliable marker to differentiate benign from malignant ovarian tumors. Further experimental studies are warranted to understand the impact of the IGF-I system in ovarian carcinogenesis.