Few data are available regarding endometrial histologic features in asymptomatic perimenopausal and postmenopausal women. This study encompasses endometrial biopsy specimens obtained from 801 such women before enrollment in a multicenter study of estrogen-progestin replacement. One endometrial cancer was found (0.13%); four additional biopsy specimens showed atypia (total 0.63%). The endometrium was atrophic in 373 (46.9%), proliferative in 133 (16.7%), secretory in 54 (6.8%), and hyperplastic in 41 (5.2%). Insufficient tissue for diagnosis was obtained in 195 (24.5%). We conclude that the yield for neoplasia is so low that screening endometrial biopsy is not justified in asymptomatic perimenopausal and postmenopausal women.