The objectives of this study were: 1) to evaluate findings in follow-up hysterectomy specimens after a diagnosis of complex atypical hyperplasia or carcinoma in endometrial polyps (EMPs) for possible significance in management strategies; and 2)to identify features in these polyps, that are predictive of the presence of endometrial hyperplasia or carcinoma in subsequent hysterectomy. Records of all cases of EMPs with endometrial hyperplasia were retrieved from the files of New York University Medical Center from 1993 to 2005. Those cases with follow-up hysterectomy were selected for the study. Of the 29 patients with complex atypical hyperplasia within the polyp, 19 out of 29 (66%) patients had hyperplasia of the non-polyp endometrium, and adenocarcinoma was observed in 9 out of 29 (31%) patients on follow-up hysterectomy. The percentage of polyp area involved by the hyperplasia was predictive of finding endometrial disorder in subsequent hysterectomy (P = 0.005). Of the 8 patients with adenocarcinoma in situ (AIS) within the polyp 3 (38%) had myoinvasive adenocarcinoma. In contrast, in cases without AIS, 4 out of 21 (19%) had myoinvasive adenocarcinoma in follow-up hysterectomy. Eight of the nine cases with carcinoma in endometrial polyp had endometrial pathology on hysterectomy. Approximately two thirds of the patients with hyperplasia and 90% of patients with adenocarcinoma in endometrial polyps show endometrial pathology on subsequent hysterectomy. The above findings reinforce the need for hysterectomy especially in postmenopausal women with atypical complex hyperplasia or carcinoma in endometrial polyps even if these changes appear confined to the polyp in initial sampling.