Ovarian cancer is the most lethal of the gynecologic malignancies, in part because the lack of striking symptoms in many women often results in diagnosis only after the disease has spread. In order to develop rational biologic or pharmacologic therapies, it is important to understand the biology of both normal and malignant ovarian epithelial cells. This review will summarize current knowledge of the expression and function of proteins in the insulin-like growth factor system in ovarian epithelium, including the peptide ligands, receptors, binding proteins, and binding protein proteases. All components of this complex regulatory system are present in the ovarian epithelium and may play important roles in regulating the normal biology of ovarian surface epithelial cells or the transformed phenotype of ovarian carcinoma cells.