A variety of vaginal and cervical abnormalities have been encountered in the offspring of women who have taken stilbestrol or chemically related nonsteroidal estrogens during pregnancy. Cervical erosion has been noted most often, but vaginal adenosis has been proven by biopsy in over 30 percent, and transverse vaginal and cervical ridges have been seen in approximately 10 percent of the exposed population. Although the use of these drugs had been widespread during the last two decades, the Registry of Clear-Cell Adenocarcinoma of the Genital Tract in Young Females has been able to collect only 170 cases of vaginal and cervical cancers of this type from all over the world. It is important that cytologists and pathologists become familiar with the various non-enoplastic and neoplastic disorders related to these hormones in order that additional epidemiologic, clinical and pathological information be acquired without delay.