N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a biologically inert cleavage product of a peptide formed in response to myocardial wall stress. In adults, NT-proBNP is used for diagnosis and risk stratification of heart failure and to monitor disease progression1,2 but it can also be used to screen for subclinical cardiovascular disease (including stage A heart failure)3. NT-proBNP is used in the management of children with congenital cardiac abnormalities and children receiving cardiotoxic chemotherapies4,5, but it is not commonly measured in otherwise healthy children. Recent studies have reported reference ranges for NT-proBNP in children6, 7, 8, 9, 10 and have shown that NT-proBNP levels can be very high immediately after birth but decrease substantially over the next few days and months. Some studies have shown differences in NT-proBNP levels by sex and by age through adolescence7,8,10,11, but other factors associated with levels of NT-proBNP in youth have not been thoroughly investigated. Additionally, most studies of NT-proBNP in healthy children have been done in largely White populations, typically from a single city or region7, 8, 9,11,12, and representative data from US children are lacking. Prior studies in adults have shown that NT-proBNP is lower in Black adults13, but associations with race and ethnicity are poorly understood in children. Higher quality of diet, male sex, insulin resistance, and obesity have also been shown to be associated with lower NT-proBNP in adults14,15, but these associations are not well characterized in youth. We examined demographic, lifestyle, and cardiometabolic factors associated with NT-proBNP levels in a nationally representative population of racially and ethnically diverse US youth.