We investigated the relation of overweight and obesity with cancer in a population-based cohort of more than 145 000 Austrian adults over an average of 9.9 years. Incident cancers (n=6241) were identified through the state cancer registry. Using Cox proportional-hazards models adjusted for smoking and occupation, increases in relative body weight in men were associated with colon cancer (hazard rate (HR) ratio 2.48; 95% confidence interval (CI): 1.15, 5.39 for body mass index (BMI) > or =35 kg m(-2)) and pancreatic cancer (HR 2.34, 95% CI: 1.17, 4.66 for BMI>30 kg m(-2)) compared to participants with normal weight (BMI 18.5-24.9 kg m(-2)). In women, there was a weak positive association between increasing BMI and all cancers combined, and strong associations with non-Hodgkin's lymphomas (HR 2.86, 95% CI: 1.49, 5.49 for BMI> or =30 kg m(-2)) and cancers of the uterine corpus (HR 3.93, 95% CI: 2.35, 6.56 for BMI> or =35 kg m(-2)). Incidence of breast cancer was positively associated with high BMI only after age 65 years. These findings provide further evidence that overweight is associated with the incidence of several types of cancer.