The cytologic findings in 15 endometrial hyperplasias were compared with those of normal endometrium and well-differentiated endometrial adenocarcinoma. Differences in tumor diathesis, hypercellularity, uneven internuclear distance, severe piling up of nuclei, anisokaryosis, nuclear size and macronucleoli were the main cytologic findings that were noted among the three conditions. These features varied in the different types of endometrial hyperplasia. It is not clear that these cytologic findings can be used to cytologically diagnose endometrial hyperplasia because some of the findings involve subjective judgments by different cytologists. Further studies on larger series of cases will be necessary to establish the cytologic criteria for the correct interpretation of endometrial abnormalities.