mammary fibromatosis is a rare pathology. It constitutes 0.2% of breast cancers, and case in men are exceptional. The definitive diagnosis is histological. we report the case of a male of 52 years, diagnosed with breast fibromatosis after pathologic study of tumor in the right breast. Programmed surgery for excision with wide margins was done. We performed a mastectomy of the subcutaneous fibromatosis with a pathologic study with clear margins. The postoperative course was uncomplicated and did not require adjuvant therapy. At 6 months follow-up he remains free of disease. The treatment of choice is surgical excision with wide margins. Adjuvant treatment is controversial. the fibromatosis in the breast is very rare and an exceptional occurrence in men. Surgery is the definitive treatment; few results exist for adjuvant therapy.