Fibromatosis of the breast is a rare benign tumor that should be included in the differential diagnosis for breast cancer. It is usually indistinguishable from malignancy on ultrasound, mammography, physical examination, and on gross evaluation. Distinction is easily made by histologic findings. This benign tumor does not metastasize, but is locally aggressive and tends to recur postoperatively, which accounts for considerable morbidity. We present two cases and a discussion from the perspective of the radiologist, the surgeon, and the pathologist.