Metastatic foci to the breast resulting from extramammary malignant neoplasm are rare and multiple myeloma involved the breast are extremely rare. A 53 year old woman with a history of multiple myeloma, diagnosed 4 years previously, was admitted with a lump in her right breast. A multiple course of chemotherapy was administered. Examination revealed a palpable mass in the upper outer quadrant of the right breast. The firm and mobile mass measured 3×2 ㎝. There was no palpable axillary lymphadenopathy. Two echo-poor solid masses were present on breast ultrasound and there was evidence of neovascularization on color Doppler. A mammogram revealed a circumscribed spheroid shadow without evidence of microcalcification, spiculation or any other signs of desmoplastic response. A core biopsy revealed immature plasma cell infiltration showing kappa light chain restriction, consistent with multiple myeloma involving the breast. Another case of breast metastasis of multiple myeloma origin is described and a review of the literature is discussed.