BACKGROUND: Consumption of wholegrain (WG) products may protect against colon and rectal cancer. METHODS: The associations between total and individual WG product consumption and colon and rectal cancer risk were prospectively examined using data on 461 incident cases of colon cancer and 283 incident cases of rectal cancer that developed during 10.6 years (median) of follow-up among 26 630 men and 29 189 women taking part in the Diet, Cancer and Health cohort. Incidence rate ratios (IRRs) of colon and rectal cancer related to total or individual WG product intake were calculated using Cox regression. RESULTS: Higher WG product intake was associated with lower risk of colon cancer and rectal cancer in men. The adjusted IRR (95% CI) was 0.85 (0.77-0.94) for colon cancer and 0.90 (0.80-1.01) for rectal cancer per daily 50 g increment in intake. For colon cancer the association was confined to intake of WG bread in particular. No consistent associations between total or individual WG product consumption and colon or rectal cancer risk were observed in women. CONCLUSION: The findings suggest that higher total WG product intake is associated with a lower risk of colon and perhaps rectal cancer in men, but not in women.