In cytological impression preparations of the endometrium practically only superficial epithelia were obtained and evaluated. In half of the sexually mature and premenopausal women a corresponding secretory change was found in the middle or in the late luteal phase only. Atypical surface epithelia are only to be observed at the beginning of the proliferation phase, in regeneration after abrasion, in chronic endometritis, with a fitted intrauterine pessary, estrogen therapy and in pregnancy and may lead to false positive results. In postmenopausal women a third of glandular hyperplasias with exuberant growth in the depths of the mucosa show superficial resting or only a few active epithelial cells which may lead to underestimation of the results, occasionally, in the case of an incipient well-differentiated carcinoma even to a false negative assessment.