We report her on a case of adenoid cystic carcinoma (ACC) associated with adenomyoepithelioma of the breast in a 73-year-old woman. ACC accounts for about 0.1% of all breast cancers. The patient presented with a large, nodular, rubbery mass that measured 5.5×4.0 cm in the subareolar region of the left breast. Light microscopy revealed various growth patterns of ACC with the adenomyoepitheli oma. Immunohistochemically, the epithelial cells in the ACC component reacted strongly for cytok eratin. The myoepithelial cells stained for smooth muscle actin, vimentin and S-100 protein, whereas staining for cytokeratin was weak. The adeno myoepithelioma component showed a similar staining pattern. Reactivity for both estrogen receptor (ER) and progesterone receptor (PR) were negative. There seems to be a spectrum of adeno myoepithelioma-related epithelial and myoepithelial lesions that ranges from low grade to high grade. Therefore, we suggest the present case of ACC arose from an adenomyoepithelioma or there is a close relationship among these combined epithelial and myoepithelial tumors. For both mammary ACC and adenomyoepitheliomas, complete excision with a margin of uninvolved tissue is the recommended treatment. Most of these patients will have an excellent prognosis.