The developed protocol for the assay of hPRL is suitable for the assessment of PRL in tissues of patients with benign and malignant serous ovarian tumors. A higher incidence of prolactin was obtained in malignant than in benign serous ovarian tumors in tissues and sera. The kinetic studies of 125I-anti hPRL antibody with hPRL in premenopausal and postmenopausal patients with benign and malignant serous ovarian tumors showed that the binding reaction is a temperature and time dependent process. The results indicate that the reaction fits pseude-first order kinetic. The results obtained from the thermodynamics studies on the association of 125I-anti hPRL antibody with hPRL in benign and malignant serous ovarian tumors were spontaneously occurred and the binding reactions were entropically driven. The spectroscopic studies revealed that each of (125I-anti hPRL antibody/PRL) complex and 125I-anti hPRL antibody has a characteristic spectrum.