Fifty consecutive cases of male breast cancer (MBC) treated in a single institution were studied. Presentation of the disease, histology, pattern of relapse, and major prognostic factors were similar to those known in female breast cancer (FBC). Five-year disease-free interval and survival were 59% and 75% respectively. Endocrine therapy for treatment of metastatic MBC was proven to be effective with a response rate of about 50% of patients, unselected with regard to oestrogen receptors. A group of patients receiving adjuvant treatment showed lower recurrence rate and a trend toward better outcome than similar stage patients without adjuvant treatment. The present study combined with the recent literature suggests that MBC and FBC are biologically comparable and that inference from experience in treatment of FBC may be justified.