Metastasis of breast cancer is examined by the database of the Annuals of the Pathological Autopsy Cases in Japan from 1981 to 1983. Breast cancer metastases to the lungs (70.3%), liver (58.4%), bone marrow (53.1%), pleura (29.0%), adrenals (27.9%), skin-subcutaneous tissue (19.7%), brain (14.3%) are frequent in decreasing order. Bone marrow, adrenals, ovaries (11.5%) and thyroid gland (11.1%) are more likely invaded by breast cancer than others. After menopause, the metastases become less frequent than before, especially after 65 years. Breast cancer is one of the highly widespread metastatic cancers, such as malignant melanoma, neuroblastoma, leukemia and malignant lymphoma. On the contrary, cancers metastatic to the breasts are rare (less than 1%). There is no special cancer metastatic to the breast.