The role of steroid receptor has been widely studied and well established in the field of breast cancer. In contrast of breast cancer, the clinicopathological roles of steroid receptors in benign breast diseases were not established clearly until now. Authors evaluated steroid receptor expressions of benign breast diseases using the immuno-histochemical staining and analyzed their relationship with pathologic types and the correlation between the positivity of steroid receptor expression and the proliferative activity of ductal epithelial cells. The results were follows; 1) The assayed tissue specimens were 93 cases which consisted with fibrocystic disease. 39 cases and fibroadenoma, 54 cases. 2) The positivity rate of steroid receptor expression in fibroadenoma (ER: 59.2%, PR: 75.9%) seemed to be more higher than in fibrocystic disease (ER: 46.1 %, PR: 55.5%), without a statistical significance. 3) The positivity rate of ER expression of fibrocystic diseases developed in premenopausal women (54.8%) was significantly higher than in postmenopausal women (2.5%). 4) Any significant correlation was not noted between the positivity of steroid receptor expression in the tissue and ductal epithelial proliferative activity. In conclusion, fibrocystic diseases and fibroadenomas possessed a significant amount of steroid receptor positive cells in their tissues. However. the positivity of steroid receptor expression in the tissues seemed to have few correlation with the ductal epithelial cellular proliferation.