The authors investigated the association of dietary patterns and type 2 diabetes in a 4-year prospective study of 36,787 adults in the Melbourne Collaborative Cohort Study (1990-1994). A total of 31,641 (86%) participants completed follow-up, and 365 cases were identified. Four factors with eigenvalues of greater than 2 were identified using the principal factor method with 124 foods/beverages, followed by orthogonal rotation. Variables with factor loadings having absolute values of 0.3 or greater were used in interpreting the factors. Odds ratios for diabetes incidence across quintiles of factor scores were computed by use of logistic regression, adjusting for age, energy intake, family history of diabetes, country of birth, and other factor scores. Factor 1, characterized by olive oil, salad vegetables, and legumes and by avoidance of sweet bakery items, margarine, and tea, was associated with country of birth but not with diabetes. Factor 2, characterized by salad and cooked vegetables, was inversely associated with diabetes. Factor 3, characterized by meats and fatty foods, was associated with increased diabetes risk. A range of fruits loaded strongly on factor 4, which showed little association with diabetes. Avoidance of a dietary pattern including meats and fatty foods, as well as adherence to a pattern including salad and cooked vegetables, is recommended.