The 2005 Dietary Guidelines for Americans include quantitative recommendations for 2 eating patterns, the USDA Food Guide and the Dietary Approaches to Stop Hypertension (DASH) Eating Plan, to promote optimal health and reduce disease risk. A Mediterranean dietary pattern has also been promoted for health benefits. Our objective was to determine whether adherence to the USDA Food Guide recommendations, the DASH Eating Plan, or a Mediterranean dietary pattern is associated with reduced risk of distal colorectal adenoma. In the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, men and women aged 55-74 y were screened for colorectal cancer by sigmoidoscopy at 10 centers in the U.S. After adjusting for potential confounders, men who most complied with the USDA Food Guide recommendations had a 26% reduced risk of colorectal adenoma compared with men who least complied with the recommendations (OR USDA score >or= 5 vs. <or=2 = 0.74, 95% CI = 0.64-0.85; P-trend < 0.001). Comparable results were found for men who had intakes most similar to the DASH Eating Plan or a Mediterranean dietary pattern. Women who most complied with the USDA Food Guide recommendations had an 18% reduced risk for colorectal adenoma, but subgroup analyses revealed protective associations only for current smokers (OR USDA score >or= 5 vs. <or=2 = 0.52, 95% CI = 0.31-0.89; P-trend < 0.01) or normal-weight women (OR USDA score >or= 5 vs. <or=2 = 0.74, 95% CI = 0.55-0.99; P-trend = 0.08). Following the current U.S. dietary recommendations or a Mediterranean dietary pattern is associated with reduced risk of colorectal adenoma, especially in men.