Risk factors for pancreatic cancer, other than smoking and diabetes, are not well-established, especially for women. In a cohort of 1.3 million middle-aged women, followed for 9.2 million person-years for cancer incidence and 11.5 million person-years for mortality, there were 1,338 incident pancreatic cancer cases and 1,710 deaths from the disease. Using proportional hazards models, we calculated adjusted relative risks (RRs) and 95% confidence intervals (CIs) by smoking, height, body mass index (BMI), alcohol consumption, physical activity and history of diabetes. Pancreatic cancer incidence was greater in current than never smokers (RR 2.39, CI 2.10-2.73), the risk increasing with the number of cigarettes smoked. The incidence of pancreatic cancer also increased with increasing BMI (RR 1.34, CI 1.13-1.57 for BMI >or= 30 vs. 22.5-25 kg/m(2)), and with a history of diabetes (RR 1.58, CI 1.22-2.03, with vs. without such a history). These factors were also associated with increased mortality from pancreatic cancer. Height, alcohol consumption and physical activity showed little or no association with pancreatic cancer risk.