Abstract It is apparent from the foregoing review that a controversy exists as to whether carcinosarcoma of the endometrium is a distinct clinical entity or merely a variation of the usual carcinoma of the endometrium. The opinions of eminent authorities like Willis and Novak, who incline to the latter theory, cannot be disregarded. It is their belief that the histologic appearance of the tissue in these cases is the result of sarcomatous metaplasia secondary to exudation and inflammation which accompany tumors of the endometrium. On the other hand, evidence has been recorded by other astute observers to the effect that a malignant endometrial neoplasm exists which differs from the commonly occurring variety of adenocarcinoma both in pathology and clinical behavior, especially in its rapidly fatal course, despite the institution of all forms of therapy which have had fairly favorable results in the management of carcinoma of the endometrium. After a review of the evidence, it would seem in the interest of clarity that the diagnosis of “carcinosarcoma” should be deleted from the nomenclature and a separate category of “pleomorphic carcinoma” recognized as a distinct subdivision of carcinoma of the endometrium. Thus, whenever sarcomatous metaplasia is noted histologically, one might anticipate a clinical course entirely different from that which is usually associated with adenocarcinoma of the endometrium. The usual forms of treatment (x-ray, radium, hysterectomy) which have a moderate success in the usual case of adenocarcinoma of the endometrium could not be considered as equally efficacious in those of what may be recognized as “pleomorphic carcinomas.” Whatever the treatment in such cases, the inevitable prognosis would appear to be rapid metastases with a fatal termination within a relatively short period.