Our objective was to identify the mammographic findings of breast cancer in men. The mammograms of 23 men with proved breast cancer (mean age, 63 years; range, 44-86 years) were retrospectively reviewed. Medical histories included gynecomastia in five, prior cancer in three, and radiation exposure in two. The most common signs were a mass in 13 and bloody nipple discharge in eight. Carcinoma was evident mammographically as an uncalcified mass in 17 patients (74%) and as a mass with microcalcifications in two patients (9%). Three tumors were not evident on mammograms, including one that was obscured by gynecomastia. Tumors were largely subareolar (14/17, 82%), and all were ductal cancers, including six pure intraductal carcinomas. Mammograms of men with breast cancer usually show an uncalcified subareolar mass, which may mimic or be obscured by gynecomastia. If calcifications are present, they may not have a pattern usually associated with malignancy.