Summary. Nonalcoholic steatohepatitis (NASH) occurs not only in adults but also in children. NASH is diagnosed in obese children with increased aminotranspherases, characteristic ultrasonography and typical percutneous liver biopsy (fat vacuoles in hepatocytes, different stages of inflammation with or without liver fibrosis) when other possible causes of steatosis are excluded. It is important to diagnose NASH and start the treatment as early as possible in order to prevent irreversible liver damage. The first line therapy consists of reduction of body weight by low-calorie diet and exercising. Ursodeoxycholic acid has been used as adjuvant therapy mainly in adults, and vitamin E also in children. We presented 5 cases with NASH (2 girls, 3 boys; age 11–15 years). All were obese and had increased transaminases, and ultrasonography and liver biopsy typical for NASH. With low-calorie diet in all our patients BMI declined, transaminases normalized).