Androgens have been frequently used in the treatment of breast cancer. However, objective responses seem to vary according to the steroid hormone receptor expression of the tumor. We have studied the relationship between concentrations of androgen receptors (AR) and those of estrogen (ER) and progesterone (PR) receptors by multiple regression and stratified analysis techniques in 154 cases of primary breast carcinomas and 39 cases of benign tumors. Both the proportion of AR-positive tumors and the concentration of AR were dependent upon the coexpression of ER and PR by the specimens. This association was evident for malignant tumors with predominance of the positive correlation between AR and ER over that of AR and PR in post-menopausal patients. In premenopausal women, ER and PR concentrations were similarly correlated with AR levels. The PR, but not the ER concentration, was positively correlated to AR levels in benign breast tumors. These findings were confirmed by multiple regression, taking into consideration additional information about the patients to build statistical models allowing prediction of AR. Among the other variables considered in building these models--age, menopausal status, weight, height, and clinical stage--only height (using data from all patients) and age (data from post-menopausal women) emerged in addition to ER and PR as significantly explaining the variability of AR as the dependent variable.