PURPOSE: To analyze the radiologic findings of metastatic tumors of the breast. MATERIALS AND METHODS: We retrospectively analyzed the findings of mammography (n=12), ultrasonography (n=9) and CT (n=4) of 13 patients with metastatic tumors of the breast. Methods for confirmation were biopsy (n=8) and clinical follow-up (n=5). The patient's ages ranged from 24 to 63 (mean 43) years. RESULTS: Primary malignancies were contralateral breast cancer (n=3), non-Hodgkin's lymphoma (n=3), stomach cancer (n=2), uterine cervix cancer (n=1), laryngeal cancer (n=1), esophageal melanoma (n=1), malignant thymoma (n=1), and lung cancer (n=1). Patterns of metastasis from contralateral breast cancer and the stomach cancer were diffuse and infiltrative, while metastasis from other cancers was of the focal massforming type. The radiologic findings of metastasis from contralateral breast cancer (n=3) were diffuse skin thickening and increased density or echogenicity in the medial aspect of the breast, while in cases involving metastasis from stomach cancer (n=2) radiographs revealed extensive skin thickening, increased density or echogenicity, lymphedema and ipsilateral lymphadenopathy in the left breast. In cases of metastatic tumors to the breast in which focal masses were seen on mammography (n=7), marginal spiculation or microcalcification of the tumors was not present. In six such cases, ultrasonography revealed well-defined margin, posterior acoustic shadowing or an irregular thick echogenic boundary was not seen. In two patients who underwent CT scanning, well-defined masses with moderate contrast enhancement were present. CONCLUSION: Radiographs of metastatic tumors to the breast from contralateral breast cancer and stomach cancer showed diffuse infiltration. The metastatic tumors with focal masses showed oval to round, smooth-marginated, well-defined masses without spiculation or microcalcification on mammography, and a well-defined mass without posterior acoustic shadowing or irregular thick echogenic boundary on ultrasonography.