The purpose of this project is to add approximately 22,500 person years for the detection of cancer and other major medical illnesses among the 5,464 women who have previously been enrolled in the DESAD Project. This continued surveillance will enable us to accomplish five specific aims: to determine the magnitude of the excess of squamous neoplasia in exposed over unexposed women and to determine if the increased risk continues over the next five years, to determine if the risk of adenocarcinoma increases during the next five years, to determine the rates of serious medical illnesses in the DES exposed women and to compare these rates with the control groups and published age specific incidence rates for the same diseases, to determine the frequency of abdominal and gynecologic surgery among DES exposed women and to compare these rates with the unexposed controls and the rates available from the National Center for Health Statistics, and to maintain contact with the DESAD Project exposed cohort at minimal expense. These aims will be accomplished by soliciting information by the method of mailed questionnaire. Each participant will be questioned annually concerning the diagnosis of medical diseases or the performance of surgical procedures. Previous experience of the DESAD cohort has indicated that in excess of 90 percent of the women previously enrolled in the project can be expected to comply with the requests for information. The sample size considerations are explained in detail in the project and indicate that it will be possible to detect, with a power of .9, a two-fold difference in the rates of many common medical diseases and surgical procedures at the p=.05 level.