Childhood obesity is increasingly recognized as an epidemic, but the economic consequences have not been well quantified. We evaluated trends in obesity-associated hospitalizations, charges, and costs using 1999-2005 data from a nationally representative sample of admissions to U.S. hospitals. We detected a near-doubling in hospitalizations with a diagnosis of obesity between 1999 and 2005 and an increase in costs from $125.9 million to 237.6 million (in 2005 dollars) between 2001 and 2005. Medicaid appears to bear a large burden of hospitalizations for conditions that occur along with obesity, while private payers pay a greater portion of hospitalization costs to treat obesity itself.