Because a few ovarian adenocarcinomas respond favorably to endocrine therapy, we tested the hypothesis that some ovarian adenocarcinomas have functional similarity with sex-hormone-sensitive endometrial and breast tumors. Cytosols from 23 ovarian adenocarcinomas and 27 control tissues were examined for receptorlike estrogen and/or progestin binding. Eight of 16 primary ovarian adenocarcinomas had estrogen and/or progestin receptorlike components; among the metastases tested, one third retained estrogen binding. No correlations were found between binding characteristics and histopathologic grade. The presence of estrogen binding in a lung lesion helped confirm recurrent ovarian disease. Estrogen binding occurred in specimens from women with no histories of exposure to exogenous estrogen. Because tamoxifen and nafoxidine could inhibit estradiol binding, it is likely that anti-estrogens will prove beneficial against some ovarian cancers.