BACKGROUND AND AIMS: To examine differences in cardiometabolic risk factors between children of different BMI and fitness levels. METHODS AND RESULTS: From a representative sample of 1222 boys and 1188 girls, aged 9-13 years, anthropometric, body composition, physical activity, cardiorespiratory fitness, biochemical and blood pressure data was collected. The prevalence of overweight and obesity was 29.9% and 11.8% respectively. In both genders, plasma HDL cholesterol concentration was higher in the 'leaner and less fit' group (lowest quartile of BMI and lowest quartile of fitness) compared to the 'heavier and more fit' (highest quartile of BMI and highest quartile of fitness) and intermediate (all other children) groups (p < 0.05). Furthermore, the 'leaner and less fit' groups in both genders had lower triacylglycerol concentration, total-to-HDL cholesterol ratio, HOMA-IR, insulin and systolic blood pressure levels compared to the 'heavier and more fit' and/or intermediate groups. Similar trends were observed for hypertension in boys and insulin resistance for both genders. Finally, the effect size of being 'leaner and less fit' on serum levels of cardiometabolic risk indices was mainly small to medium (i.e. Cohen's d 0.2-0.5). CONCLUSION: Leaner and less fit boys and girls had better cardiometabolic risk profiles than their heavier and more fit peers, probably suggesting a higher importance of leanness over fitness in children from a cardiometabolic health benefit perspective.