Objective: Atypical endometrial hyperplasia (AEH) has been associated with the presence of concomitant endometrial carcinoma (EC). The aim of this study is to examine the frequency of coexisting endometrial carcinoma when atypical endometrium hyperplasia was found upon biopsy. We also evaluated the influence of preoperative diagnostic techniques (pipelle and dilation and curettage (D&C)), and the value of transvaginal ultrasound in detecting unexpected tumor invasion. Study design: Between January 1992 and December 2003, at the Department of Obstetrics and Gynecology, University of Parma, and Policlinico S. Matteo, Pavia, 70 consecutive patients subjected to total hysterectomy with a histological diagnosis of AEH were retrospectively selected. 52/70 patients underwent vaginal hysterectomy, with bilateral salpingo-oophorectomy (BSO) whereas 18/70 had abdominal hysterectomy with BSO within 8 weeks since the diagnosis of AEH. Results: We found in 30 of the 70 patients with atypical endometrial hyperplasia in the biopsy coexisting endometrial carcinoma (43%). No differences in diagnostic accuracy between the pipelle method and D&C were found. Conclusion: Transvaginal ultrasound was not a feasible method for predicting EC. After a follow-up of an average of 5 years there was, neither in the abdominal operated patients nor in the vaginal operated patients, a recurrence of disease.