AbstractObjective:To evaluate the association between nutritional quality of breakfast and cardiometabolic risk factors.Design:Cross-sectional study, 2015 Health Survey of São Paulo (2015 ISA-Capital) with Focus on Nutrition Study (2015 ISA-Nutrition).Settings:Population-based study, with a representative sample of adults and elderlies living in São Paulo, Brazil.Participants:The sample included 606 adults (aged 20–59 years) and 537 elderlies (aged ≥60 years) from the 2015 Health Survey of São Paulo. Dietary intake was assessed by at least one 24-h recall. Breakfast quality was evaluated using the proposed Brazilian Breakfast Quality Index (BQI), ranging scores from 0 to 10. BQI associations with sociodemographic, lifestyle, dietetic and cardiometabolic variables were estimated using survey-weighted multiple logistic regression models.Results:Being ≥60 years of age, self-identifying as White or Asian, having a per capita family income with ≥1 minimum wage, being sufficiently active at leisure time and non-smoker were associated with better scores of BQI. A higher BQI score was inversely associated with elevated blood pressure (OR 0·81, 95 % CI 0·70, 0·94), fasting glucose (OR 0·85, 95 % CI 0·73, 0·98), HOMA-IR (OR 0·86, 95 % CI 0·74, 0·98), total cholesterol (OR 0·87, 95 % CI 0·76, 0·99), LDL-C (OR 0·85, 95 % CI 0·74, 0·97), metabolic syndrome (OR 0·82, 95 % CI 0·72, 0·93) and being overweight (OR 0·87, 95 % CI 0·76, 0·99).Conclusions:Breakfast quality of Brazilian adults needs improvement with disparities across some sociodemographic factors. BQI was associated with lower odds of cardiometabolic risk factors, suggesting a beneficial effect in this population and emphasising the role of breakfast in reducing the risk of CVD.