After standardization for age and menopausal status, the prevalence of estrogen receptor positivity among 88 White breast cancer patients was about .72 compared with a prevalence of about .54 among Black patients. The prevalence of progesterone receptor positivity was also higher among White than among Black patients, although the magnitude of the difference was smaller. These differences were unchanged after adjustment for tumor size and nodal and distant metastases in addition to age and menopausal status.