The clinicopathological features of 11 cases of a spindle cell carcinoma handled by our department have been investigated and are presented, with two cases that demonstrated cystic changes. Out of a total of 1,524 breast carcinomas that were treated, 11 (0.72%) were spindle cell carcinomas. The size of the tumor was generally larger than in other more common types of breast carcinomas, but the degree of a lymph node metastasis was low and the prognosis was better. As for the ER status, 4 out of 5 cases were negative. As cystic changes in the tumor were found in 5 of the 11 cases, it would seem that spindle cell carcinomas of the breast tend to show cystic changes in their tumors.