Past population studies have indicated a higher prevalence of high albumin excretion in children than in adults. In this study, NHANES III United States population data was analyzed to study factors associated with elevated albumin excretion in children 8 to 18 years of age. The analysis confirmed a higher prevalence of albumin values > 30 mg/g creatinine and > 200 mg/g creatinine in children than in adults, and indicated that girls are two to three times more likely to have albumin excretion above these levels than boys. Neither hypertension nor reported diabetes--major factors influencing albumin excretion in adults--accounted for the higher excretion levels in children. The higher excretion levels were not associated with prescription medications or a poor rating of the child's overall health status by a physician. The higher prevalences is influenced by puberty stage and is more likely to occur in children with lower than average body mass index, independent of the relationship with urine creatinine excretion. The increased prevalence of high albumin excretion is probably associated with normal development in children, but an increased susceptibility to chronic diseases in the future among the children with high excretion cannot be ruled out.