To assess the relations of infertility causes and treatment to cancer risk, we will conduct a retrospective cohort study of approximately 12,000 women evaluated for infertility between 1965-1988. These women will be ascertained from several large infertility clinics and private practices in various geographic locations in the United States: Boston, Chicago, Detroit, New York, and Palo Alto. These practices were selected on the basis of their having large number of patients who received ovulation stimulating drugs many years in the distant past. Abstractors reviewed clinic medical records to identify eligible study participants and abstract data needed to classify causes of infertility and document therapies employed. Using a variety of tracing sources (including the National Death Index, credit bureaus, and postmasters), the vital status and location of the study subjects were determined. Subjects who were traced and identified as alive are being sent a detailed questionnaire that requests information on their health status as well as on a number of lifestyle practices. For subjects who report a cancer, medical verification is being sought from the diagnosing physicians and/or facilities. Death certificates are being sought for deceased subjects.