To date, only 16 cases of transitional cell carcinoma of the endometrium and endometrial carcinoma with transitional cell differentiation have been reported in the literature. We reviewed the clinicopathologic features of 5 cases of endometrial carcinoma with transitional cell differentiation. The mean age was 68 years, and all patients presented with postmenopausal bleeding. Macroscopically, the tumors were intracavitary and friable. Microscopically, the tumors were composed of tightly packed papillary structures with thin fibrovascular cores, resembling a transitional cell carcinoma of the urinary tract. One tumor showed exclusively transitional cell differentiation, whereas the remaining 4 neoplasms showed that the transitional cell carcinoma was admixed with a variable proportions of endometrioid adenocarcinoma. Four cases were in FIGO stage IB, whereas the remaining tumor infiltrated the uterine cervix (FIGO stage IIB). Immunoreactivity was typical of müllerian derivatives (cytokeratin 7 positive, cytokeratin 20 negative). p16 protein was positive in all cases, but human papillomavirus DNA was not detected in any of the tumors. None of the patients developed local recurrence or distant metastases, even though there are too few cases of transitional cell carcinoma of the endometrium reported to make any statistically valid conclusions about response to therapy and prognosis. Transitional cell carcinoma is an unusual variant of endometrial carcinoma, with distinctive histologic and immunophenotypic features. Identification of this variant broadens the morphological spectrum of epithelial neoplasms of the endometrium.