PIP: Regarding maternal ingestion of stilbestrol to high-risk pregnant patients during the late 1940's and early 1950's and the appearance of vaginal adenocarcinoma in their female offspring years later, physicians are advised to examine patients whose mothers received stilbestrol during pregnancy. Once these females reach the menarche, periodic vaginal examinations are required. A diagnosis of cancer should be considered when abnormal vaginal bleeding occurs. It is hypothesized that these cancers originate from adenomatous vaginal lesions that become malignant. The high incidence of benign vaginal adenosis suggests that an anomaly of vaginal epithelial development may be a predisposing condition. Since reporting on 8 patients in 1970, there is more evidence of an association between maternal stilbestrol administration and vaginal cancer in the offspring. More than 80 cases of vaginal and cervical adenocarcinoma in young women have been diagnosed. In most cases the maternal medical history revealed intrauterine exposure to stilbestrol, dienestrol or hexestrol. The Food and Drug Administration has warned all physicians that stilbestrol is contraindicated in pregnant women. Physicians who are contacted by worried mothers or anxious young women can be assured that, as yet, the risk appears to be low, but the public should be made aware that adolescent females and young women who had fetal exposure to stilbestrol need regular vaginal examination.