The authors report on 767 consecutive primary Stage I-II breast cancer cases followed-up from 3 to 8 years. The estrogen receptor (ER) content was determined in all cases and did not influence the treatment choice. A correlation was attempted between ER and menstrual or pathological nodal status (N) or the 5-year disease-free survival (DFS). ER was correlated with menopausal status ER+ cases being more frequent in postmenopausal patients, whereas no correlation was observed between ER and nodal status. In absence of nodal involvement (N-) the prognosis was not influenced by the ER status. A significantly better DFS was evident for ER+ respect to ER- patients in the N+ series but such a correlation is questionable as the adjuvant treatment (hormone or chemotherapy) given to such patients may have influenced the DFS according to the ER status. According to the present study, ER determination should not be used as a discriminant in the performance of adjuvant postoperative treatment based on a prognostic judgment.