One hundred consecutive cases of hyperplasia of the endometrium were referred to the Sloane Hospital for Women. The referral diagnoses and consultation diagnoses were compared for the purpose of analyzing common diagnostic problems in interpretation of endometrial hyperplasias and the use of diagnostic terminology as it applies to prognosis and therapy. The consultation diagnosis was a down grade of the original diagnosis in 69% of the reviewed cases. The most common endometrial pathology misinterpreted as hyperplasia was endometrial polyps, followed by the endometrial metaplasias, and architectural distortion caused by necrosis and mechanical artifact. In 14% of the referral diagnoses, the use of terminology was vague, with such terms as endometrial, epithelial, or glandular hyperplasia, and did not communicate the prognostic intent of the referring pathologist to the consulting physician. The careful use of endometrial diagnostic terms accompanied by a statement of the system of classification used and its corresponding clinical intent is suggested.