Patients with post- or perimenopausal bleeding (PMB) whose initial endometrial biopsy or dilation and curettage (D&C) reveals benign or insufficient tissue may eventually be diagnosed with endometrial cancer or complex endometrial hyperplasia. We studied 286 consecutive patients with PMB who had either an endometrial biopsy or D&C at Brigham and Women's Hospital during November 1990 to April 1991 and reviewed their subsequent specimens after a minimum of 23 months of follow-up. Of the initial 286 patients with PMB, 6 (2%) had endometrial cancer on their index biopsy, 17 (6%) had complex hyperplasia, and 201 (70%) had other benign findings. Sixty-two (22%) had "tissue insufficient for diagnosis." Excluding the 23 with cancer/complex hyperplasia, there were 263 patients in the cohort, 86 of whom (33%) had further endometrial sampling during the follow-up period. Of these, four (2%) were subsequently found to have a uterine malignancy (2 of the benigns, 2 of the insufficients) and five (2%) were subsequently found to have complex hyperplasia. Of the four patients subsequently found to have cancer, two had stage I adenocarcinoma, one had stage IV adenocarcinoma, and one had stage I high-grade stromal sarcoma.