The purpose of this study was to evaluate imaging findings of metastatic disease to the breast. We analyzed 15 cases that had been previously examined by radiographic study (comprising a total of 11 mammograms, 13 ultrasounds and 3 chest CT). Primary malignancies included the following: 6 breast cancers, 5 stomach cancers, 2 melanomas, 1 cervical cancer, and 1 lung cancer. Radiologic findings were analyzed and the 15 cases were divided into two groups: hematogeneous and lymphangitic metastasis. Eleven cases were classified as lymphangitic metastasis (73.3%) and 4 cases were hematogeneous metastasis (26.7%). Multiple masses were shown in 13 cases (86.7%), and 12 cases displayed unilateral lesions (80%). There was no evidence of calcification. In the 11 cases with available mammogram, 7 cases (63.6%) revealed multiple masses with well-defined (2 cases, 28.6%) or ill-defined margin (5 cases, 71.4%) and 6 cases (54.5%) showed diffuse increased density and skin thickening. Among the 11 cases that revealed mass lesions on ultrasound, 2 cases showed a well-defined margin (18.2%) and 9 cases showed an ill-defined margin (81.8%). Posterior shadowing of the mass was seen in only 1 case. Four cases (36.3%) showed a minimal echogenic boundary around the mass. Eight cases showed diffuse skin thickening (53.3%). Three cases with chest CT showed multiple masses and/or diffuse skin and trabecular thickening of the breast. In conclusion, the characteristic imaging findings of metastatic disease to the breast are multiple ill-defined masses with a lack of desmoplastic reaction and no calcification, as compared to primary breast carcinoma. The diffuse lesions without evidence of breast mass on mammogram and US could be distinguishable from inflammatory carcinoma of breast origin.