Estrogen (ER) and progesterone receptors (PR) were analyzed in the cytosol and nuclei prepared from specimens of human uterine tissue of patients with certain disorders identified as hyperplasia endometrii adenomatosa, myoma uteri per magnum, adenocarcinoma endometrii and adenocarcinoma corporis uteri. These investigations have revealed a different level of ER and PR in analyzed tissue specimens, as well as the existence of a relationship between changes in receptor levels and respective Kd. These changes suggest a correlation between steroid receptor levels and the type of tissue transformation. The functionality of the receptors was analyzed by the ultracentrifugation of non-activated and activated steroid-receptor complexes in sucrose density gradients, as well as by the investigation of their interaction with isolated nuclei. These results indicate that some changes in steroid receptor molecules can be detected when the tissue turns from normal to malignant transformation. On the basis of this investigation it could be proposed that the analysis of activated and non-activated steroid-receptor complexes by means of the methods used in this study can be applied as a useful clinical tool in the determination of the endocrine dependence of transformed tissues, as well as for the optimum dosing of individual treatment of patients with uterine and other tissue carcinoma