Microglandular adenocarcinoma of the endometrium may cause diagnostic problems because of its bland cytologic appearance and its histologic similarity to benign microglandular hyperplasia of the cervix. We present two cases of microglandular adenocarcinoma and discuss the clinical, pathologic, and immunohistochemical findings. Both patients were postmenopausal women, one of whom was taking exogenous hormones. Endometrial biopsy specimens contained polypoid tissue fragments, within which were microcystic spaces lined by flattened, cuboidal, or columnar cells. Solid nests or sheets of tumor cells surrounded glands in some tissue fragments. The nuclei were uniform and bland, and mitotic figures, although readily identifiable, were infrequent (1 per 10 high-power fields). A majority of tumor cells contained intracytoplasmic mucin. Numerous neutrophils were present in gland lumens and tissues. Immunohistochemical stains for carcinoembryonic antigen and TAG72 (B72.3) revealed focal moderate to intense apical and cytoplasmic staining; immunostains for p53 protein were negative. One carcinoma was confined to the endometrium, whereas the other invaded into the inner one-third of the myometrium. Both patients were well after a limited follow-up of 1 year. Microglandular adenocarcinoma is a distinctive variant of endometrial carcinoma that is most likely a form of mucinous adenocarcinoma.