This is a follow-up study of male and female offspring of mothers who were part of a double-blind placebo controlled investigation during the years 1951-1952, originally aimed at determining the usefulness of DES administration in maintaining pregnancy. So far, 84 DES-exposed females, 43 female controls, 42 DES-exposed males and 37 male controls have been examined. Circumferential ridges of the vagina and cervix were seen in 39% of the DES-exposed females but in none of the controls. Colposcopy revealed vaginal epitheleal changes in 78% of the DES-exposed females 2% of the female controls. Cytology proved to be reliable as a screening test for vaginal epithelial changes in the DES-exposed female. Urine cytology was negative for tumor cells in all patients. The main abnormal finding in the DES-exposed males was that cysts in the epididymis were detected in 10%. No cases of cancer were observed in either the male or female offspring.