ObjectiveTo estimate the dietary share of ultra-processed foods and to determine its association with the overall nutritional quality of diets in Brazil.DesignCross-sectional.SettingBrazil.SubjectsA representative sample of 32 898 Brazilians aged ≥10 years was studied. Food intake data were collected. We calculated the average dietary content of individual nutrients and compared them across quintiles of energy share of ultra-processed foods. Then we identified nutrient-based dietary patterns, and evaluated the association between quintiles of dietary share of ultra-processed foods and the patterns’ scores.ResultsThe mean per capita daily dietary energy intake was 7933 kJ (1896 kcal), with 58·1 % from unprocessed or minimally processed foods, 10·9 % from processed culinary ingredients, 10·6 % from processed foods and 20·4 % from ultra-processed foods. Consumption of ultra-processed foods was directly associated with high consumption of free sugars and total, saturated and trans fats, and with low consumption of protein, dietary fibre, and most of the assessed vitamins and minerals. Four nutrient-based dietary patterns were identified. ‘Healthy pattern 1’ carried more protein and micronutrients, and less free sugars. ‘Healthy pattern 2’ carried more vitamins. ‘Healthy pattern 3’ carried more dietary fibre and minerals and less free sugars. ‘Unhealthy pattern’ carried more total, saturated and trans fats, and less dietary fibre. The dietary share of ultra-processed foods was inversely associated with ‘healthy pattern 1’ (−0·16; 95 % CI −0·17, −0·15) and ‘healthy pattern 3’ (−0·18; 95 % CI −0·19, −0·17), and directly associated with ‘unhealthy pattern’ (0·17; 95 % CI 0·15, 0·18).ConclusionsDietary share of ultra-processed foods determines the overall nutritional quality of diets in Brazil.