Between 1982 and 1991, 76 of 322 (24%) patients with primary endometrial adenocarcinoma and morphologic risk factors underwent surgery including systematic pelvic lymphadenectomy (LA). A mean number of 37 lymph nodes per patient was removed. The number of removed nodes did not differ with respect to mode of LA, FIGO stage, depth of myometrial invasion, and histologic subtype or grade. Twenty-seven of 76 (36%) patients had lymph node metastases; 37% of lymph node metastases were < or = 2 mm in diameter. The incidence of lymph node metastases correlated significantly with the depth of myometrial invasion but not with histologic subtype and grade. Twenty-four patients with positive nodes who had stage I disease according to the clinical classification (FIGO 1971) were upstaged to stage IIIc according to the surgical staging system (FIGO 1988). This study underlines the need for complete, systematic LA and the need for thorough histologic processing with step-serial sections for correct staging of patients with endometrial cancer.