The aim of this study was to underline the frequently seen problems in diagnosing the lesions seen in the hyperplasia-carcinoma sequence by evaluating the variances between the observers. Four pathologists re-evaluated 137 endometrial biopsies and grouped them into diagnostic categories. The results were analyzed by Kappa statistics. Full agreement was reached in 89 cases (64.96%), with Kappa values ranging between 0.63-0.74. Three observers rendered the same diagnosis in 34 (24.81%) cases, and only one pathologist disagreed. Two or more observers held different views in 16 cases (10.95%). The problem areas were as follows: criteria distinguishing simple hyperplasia from other benign lesions, discrimination between atypical hyperplasia and carcinoma, and decision-making regarding the presence of atypia. There was a tendency towards overdiagnosis of hyperplasia in our department. Since the progression to carcinoma is a sequential event, borderline cases will exist if categories based on simple and clear cut off points are not defined.