We present a case of metastatic medulloblastoma to the breast in a 33-year-old woman who had a cerebellar medulloblastoma excised 2 years previously. Upon presentation, she had a bilateral breast tumor, which was diagnosed as a malignant small cell tumor by means of fine needle aspiration biopsy. An excisional biopsy of the tumor was performed, showing metastatic medulloblastoma, morphologically identical with a cerebellar primary. Eighteen months following breast surgery, the patient developed unilateral ovarian and peritoneal metastases and died of the disease 57 months after the cerebellar tumor was excised. Metastatic medulloblastoma to the breast is an extremely rare form of a secondary breast tumor, which may be easily diagnosed when both primary and secondary tumors are cytologically or histologically compared. If this is not possible, considerable problems may be encountered to get to the correct diagnosis.