A number of studies have examined the association between body mass index (BMI) and risk of pancreatic cancer, but uncertainty about the relationship remains. We performed a meta-analysis to summarize the evidence from prospective studies investigating this association. We searched MEDLINE for studies published in any language from 1966 to November 2006. Prospective studies were included if they reported relative risks (RRs) with 95% confidence intervals (CIs) for the association between BMI and pancreatic cancer incidence or mortality. Study-specific RR estimates were combined by use of a random-effects model. A total of 21 independent prospective studies, involving 3,495,981 individuals and 8,062 pancreatic cancer cases, met the inclusion criteria. The estimated summary RR of pancreatic cancer per 5 kg/m2 increase in BMI was 1.12 (95% CI, 1.06–1.17; p-heterogeneity = 0.13) in men and women combined, 1.16 (95% CI, 1.05–1.28; p-heterogeneity = 0.001) in men, and 1.10 (95% CI, 1.02–1.19; p-heterogeneity = 0.12) in women. There was no evidence of publication bias (p = 0.58). Findings from this meta-analysis of prospective studies support a positive association between BMI and risk of pancreatic cancer in men and women. © 2007 Wiley-Liss, Inc.