In the Radio Institute "O. Alberti" of Brescia from 1.1.73 to 31.12.79, 976 patients were treated with postoperative radiotherapy after radical mastectomy. The impact of therapy has been observed on the NED survival and evaluated for prognostic factors. The involvement of axillary lymph nodes appears to be the most relevant prognostic factor; the hormonal perimenopausal status was associated with a poorer prognosis both regarding the high frequency of axillary metastatic nodes and because in N+ 1-3 cases the probability of relapse is different and higher in comparison to post and premenopausal status. The site of origin of the primary tumor does not appear to be a significant prognostic factor related to the same number of nodes involved. Direct correspondence exists between diameter of the primary tumor and metastatic regional nodes. In N- patients the evaluated prognostic factors are not significant; in N+ patients the cases with a significantly different risk of relapse were identified for N+ 1-3 by the perimenopausal status and for N+ greater than or equal to 4 by the diameter of tumor. Postoperative radiotherapy alone seems to be able to modify the prognosis of operable breast cancer. The combination of local radiotherapy and adjuvant medical therapy could be a logical approach not only in order to improve the local control but also to prevent metastases.