The aim of this study was to compare cytosol estrogen (ER) and progesterone (PgR) receptor levels measured in normal and pathological tissue specimens (n = 395) of endometrium (ED), endocervical mucosa (EM) and cervical vaginal portion (VP) from 108 patients (age 27-79). The highest ER levels were found in ED which decreased to 25% in VP. The PgR decline was more pronounced in VP since the majority of samples were PgR-negative. In addition pathological tissue from ED exhibited marked differences in steroid receptor levels: The highest ER and PgR concentrations were detected in the proliferative phase, whereas the secretory phase exhibited significantly reduced ER and PgR levels. The lowest ER and PgR amounts were measured in atrophic and quiescent tissues; in proliferative tissue ER and PgR levels were comparable to hyperplastic tissue. Cervical ER and PgR concentrations were significantly lower as compared with ED (25-30%), and no cyclic variations were detectable. Also ER and PgR levels were different between EM and VP. 96% of ER were positive in the cervix, whereas 73% were PgR-negative in VP. Furthermore an inverse correlation between ER and progesterone was found in ED and a positive correlation between estradiol and PgR. These results suggest that the cytosol ER and PgR levels vary markedly in the uterine corpus and may explain in part the different response to endocrine therapy.