Nonalcoholic steatohepatitis (NASH) is one entity in a spectrum of chronic liver disease related to obesity, hyperinsulinemia, insulin resistance, and liver cell injury from free fatty acid toxicity or other oxidant stress. The more inclusive term "nonalcoholic fatty liver disease" (NAFLD) is increasingly being used to encompass the entire spectrum, which includes simple hepatic steatosis without inflammation (which may not lead to progressive liver injury), NASH itself, and the resulting cirrhosis (which may be devoid of steatosis). Children get NAFLD, and the incidence of this pediatric liver disease is rising as childhood obesity becomes increasingly prevalent. Although much remains to be learned about pediatric NAFLD, it is already evident that children with NASH risk progressive liver damage, including cirrhosis. Liver biopsy is required for definitive diagnosis, and other causes of fatty liver in childhood must be excluded. Gradual weight loss through increased regular exercise and a low-fat, low-refined carbohydrate diet appears to be effective. Drug treatments are being developed. Pediatric NASH is a serious complication of childhood obesity.