Study results regarding risks associated with reproductive characteristics and pancreatic cancer have been mixed. Using data from a population-based case-control study of pancreatic cancer, the authors assessed the role of menstrual factors, reproductive factors, and hormone use in the etiology of pancreatic cancer among women (241 cases, 818 controls). Rapid case ascertainment was used in six San Francisco Bay Area counties in California between 1995 and 1999. Controls were sampled by using random digit dialing. All statistical tests were two sided. Age at menopause (> or = 45 years vs. < 45 years) was associated with a 1.8-fold increased risk of pancreatic cancer (95% confidence interval: 1.2, 2.8). No association was found between age at menarche, parity, oral contraceptive use, estrogen replacement therapy (ERT), or history of oophorectomy and pancreatic cancer. The adjusted odds ratio for current smoking and pancreatic cancer was stronger for women who had never used oral contraceptives or ERT (odds ratio = 11.5, 95% confidence interval: 3.5, 38.1) than for those who reported using both (odds ratio = 1.7, 95% confidence interval: 0.56, 5.0). Other than a possible reduced risk estimate for smoking-related pancreatic cancer for users of exogenous hormones (oral contraceptives and ERT), results did not show a consistent pattern for reproductive factors, estrogen exposure, and risk of pancreatic cancer.