Diethylstilbestrol ( DES) is a synthetic estrogen given to pregnant women to prevent miscarriages and preterm labor; the drug was used between 1941 and 1971 in the United States and into the 1980s in other countries. DES exposure is associated with significant long-term health effects, including increased risk for breast cancer, cervical and vaginal clear cell adenocarcinoma, reproductive tract abnormalities, infertility, poor pregnancy outcomes, and early menopause. This article reviews the potential health risks associated with DES exposure, how to assess which patients are at risk, and management recommendations for patients exposed to DES.