Context: Inconsistent findings from observational studies have continued the controversy over the effects of dietary fiber on colorectal cancer. Objective: To evaluate the association between dietary fiber intake and risk of colorectal cancer. Design, Setting, and Participants: From 13 prospective cohort studies included in the Pooling Project of Prospective Studies of Diet and Cancer, 725 628 men and women were followed up for 6 to 20 years across studies. Study-and sex-specific relative risks (RRs) were estimated with the Cox proportional hazards model and were subsequently pooled using a random-effects model. Main Outcome Measure: Incident colorectal cancer. Results: During 6 to 20 years of follow-up across studies, 8081 colorectal cancer cases were identified. For comparison of the highest vs lowest study-and sex-specific quintile of dietary fiber intake, a significant inverse association was found in the age-adjusted model (pooled R R = 0.84; 95%confidence interval [CI], 0.77-0.92). However, the association wa s attenuated and no longer statistically significant after adjusting for other r isk factors (pooled multivariate RR = 0.94; 95%CI, 0.86-1.03). In categorical analyses compared with dietary fiber intake of 10 to < 15 g/d, the pooled multiv ariate RR was 1.18 (95%CI, 1.05-1.31) for less than 10 g/d (11%of the overall study population); and RR, 1.00 (95%CI, 0.85-1.17) for 30 or more g/d. Fiber intake from cereals, fruits, and vegetables was not associated with risk of colo rectal cancer. The pooled multivariate RRs comparing the highest vs lowest study -and sex-specific quintile of dietary fiber intake were 1.00 (95%CI, 0.90-1. 11) for colon cancer and 0.85 (95%CI, 0.72-1.01) for rectal cancer (P for comm on effects by tumor site = .07). Conclusions: In this large pooled analysis, die tary fiber intake was inversely associated with risk of colorectal cancer in age -adjusted analyses. However, after accounting for other dietary risk factors, h igh dietary fiber intake was not associated with a reduced risk of colorectal ca ncer. Context: Inconsistent findings from observational studies have continued the controversy over the effects of dietary fiber on colorectal cancer. Objective: To evaluate the association between dietary fiber intake and risk of colorectal cancer. Design, Setting, and Participants: From 13 prospective cohort studies included in the Pooling Project of Prospective Studies of Diet and Cancer, 725 628 men and women were followed up for 6 to 20 years across studies. Study-and sex-specific relative risks (RRs) were estimated with the Cox proportional hazards model and the following For Out of Measure: Incident colorectal cancer. Results: During 6 to 20 years of follow-up across studies, 8081 colorectal cancer cases were identified. For comparison of the highest vs lowest study-and sex-specific quintile of dietary fiber intake, a significant inverse association was found in the age-adjusted model (pooled RR = 0.84; 95% confidence interval [CI], 0.77-0.92 ) However, the association wa s attenuated and no longer quite significant after adjusting for other r isk factors (pooled multivariate RR = 0.94; 95% CI, 0.86-1.03). In categorical analyzes compared with dietary fiber intake of 10 to <15 and po, ​​RR 1.00 (95% CI, 0.85-1.17) for less than 10 g / d (11% of the overall study population) for pooled multivariate RRs comparing the highest vs lowest study-and sex-specific quintile of dietary fiber intake were 1.00 ( 95% CI, 0.90-1.11) for colon cancer and 0.85 (95% CI, 0.72-1.01) for rectal cancer (P for comm on effects by tumor site = .07). Conclusions: In this large pooled analysis, die tary fiber intake was inversely associated with risk of colorectal cancer in age -adjusted analyzes. However, after accounting for other dietary risk factors, h igh dietary fiber intake was not associated with a reduced risk of colorectal cancer.