Survival and treatment failure are analyzed in a homogeneous group of 70 pre- or post-menopausal patients with operable breast cancer and histologically involved axillary nodes. From March 1968 to December 1975, all patients underwent simple or radical mastectomy, followed by radiotherapy in 67. The period of observation varied from 11 months to 10 years. Treatment failures were observed on 34 patients: 10 loco-regional relapses, 21 distant metastatizations, and 3 tumors in the other breast. Analysis of actuarial survival curves shows a statistically significant difference between patients with 1 to 3 positive axillary nodes and patients with 4 or more, but no difference with regard to the volume of the tumor and the patient's age. Comparison of disease-free period curves shows statistically significant differences between patients aged below and over 55 years, tumor of less or more than 2 cm, and 4 or fewer axillary nodes. These results are comparable to those in the literature and form a contribution to a Swiss study of post-operative adjuvant chemotherapy in breast cancer with positive axillary nodes.