Cellular samples obtained by vaginal scrapings from 204 women exposed to diethylstilbestrol (DES) in utero were evaluated and compared with samples collected from a like number of controls. Several different sampling methods were evaluated. Vaginal scrapings contained columnar cells existing alone or in combination with squamous metaplastic cells and less frequently were characterized only by metaplastic cells. None of the control samples contained columnar cells and only 1 of 200 control samples contained metaplastic cells. The cellular findings in the offspring of women exposed to DES in utero varied in relation to age. Cellular abnormalities were demonstrated in 90.4% of women having scrapings of visible lesions and in 88.1% of women studied by 4-quadrant vaginal scrapings in the absence of clinical disease. Of 58 women with histopathologically proven adenosis, 57 (98.3%) had similar cellular abnormalities. Abnormalities were demonstrated in squamous epithelial cells of the vagina in 8 (3.9%) of the women exposed to DES in utero, and in 5 of these women there were similar changes in the uterine cervix. Only 2 (0.9%) of the women had cellular changes suggesting dysplasia of the vagina.