Histopathological assessment of tumour grade and cell type is central to the management of endometrial carcinoma, guiding the extent of surgery and the use of adjuvant radiation therapy and chemotherapy. Endometrioid carcinomas are usually low grade but high-grade examples are encountered, and they have a significantly worse prognosis, similar to that of high-grade subtypes such as serous and clear cell carcinoma. This article reviews the various grading systems that have been proposed for use with endometrioid endometrial carcinoma, and discusses the recent progress in cell type assignment, including the use of immunohistochemistry as a diagnostic adjunct.