A signet ring cell carcinoma (SRCC) associated with invasive ductal carcinoma(IDC) of the breast occurred in a 52-year-old woman. She was admitted in December 1994 for investigation of a palpable right breast mass. On physical examination a tumor measuring 2.5 x 2.1 cm was palpable in the right upper lateral portion of the breast. Ultrasonography of the breast visualized an irregular-shaped tumor. On January 1995, modified radical mastectomy was performed, and the postoperative course was uneventful. Histological examination revealed a tumor consisting of IDC with a component of SRCC that occupied about 40 % of the area of the invasive carcinoma. We reviewed the cases of IDC with SRCC from the Japanese literature with consideration of the characteristics and problems of this rare tumor.