BACKGROUND: Studies of diet and depression have focused primarily on individual nutrients. AIMS: To examine the association between dietary patterns and depression using an overall diet approach. METHOD: Analyses were carried on data from 3486 participants (26.2% women, mean age 55.6 years) from the Whitehall II prospective cohort, in which two dietary patterns were identified: 'whole food' (heavily loaded by vegetables, fruits and fish) and 'processed food' (heavily loaded by sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products). Self-reported depression was assessed 5 years later using the Center for Epidemiologic Studies - Depression (CES-D) scale. RESULTS: After adjusting for potential confounders, participants in the highest tertile of the whole food pattern had lower odds of CES-D depression (OR = 0.74, 95% CI 0.56-0.99) than those in the lowest tertile. In contrast, high consumption of processed food was associated with an increased odds of CES-D depression (OR = 1.58, 95% CI 1.11-2.23). CONCLUSIONS: In middle-aged participants, a processed food dietary pattern is a risk factor for CES-D depression 5 years later, whereas a whole food pattern is protective.