Metastatic lesions to the breast are unusual. We add 21 cases to the previously reported 131 clinical cases. The most common sources are malignant melanomas and the lymphoma/leukemia group. Metastatic lesions to the breast tend to be painless discrete lumps that are generally small at the time of discovery. They usually occur in the upper outer quadrant and are commonly associated with axillary adenopathy. Occasionally, they are the initial manifestation of an occult extramammary primary cancer. Prognosis is poor but appears slightly improved since availability of more refined chemo- and immunotherapeutic regimens. The clinical, pathologic, and radiographic features of this problem are described.