Abstract
The expression of Ca antigen in normal, hyperplastic and neoplastic endometria was studied by an immunoperoxidase technique. Ca antigen was frequently detectable in normal secretory endometrium, was found only rarely in cystic glandular hyperplasia or hyperplasia with architectural atypia, was expressed with moderate frequency in hyperplasia with cytological atypia and was invariably present in endometrial adenocarcinoma. Apparently, the Ca antigen is of no discriminatory value in differentiating between hyperplastic and neoplastic conditions of the endometrium.