Apocrine carcinoma is a rare breast cancer and its frequency is about 0.4% of all breast cancers. Little is known about its clinical behavior and prognosis. To our knowledge, few studies have reported the radiologic appearances of apocrine carcinoma in the breast and there has been no such report from Korea. We describe the sonographic findings of a case of apocrine carcinoma in the breast. The sonographic findings are microlobulated heterogeneous hypoechoic lesion that has a central markedly hypoechoic portion and a peripheral mixture of iso and hypoechgenecity.