The aim of this study was to evaluate the correlation of ultrasonography-proven fatty liver with liver functions, serum lipid levels and anthropometric measurements in children with exogenous obesity. Three hundred and twenty-two patients (183 girls, 56.8%) with a mean age of 11.4+/-3.2 years (4-18 years) who presented with the complaint of obesity were enrolled. In 38 (11.8%) patients, increased liver echogenicity resembling fatty liver was found (Group 1). The body mass index percentages of group 1 patients were significantly higher than of those without fatty liver (Group 2) (157.7+/-18.0 vs 151.3+/-17.8, p=0.038). Alanine and aspartate aminotransferase levels of group 1 patients were significantly higher than of group 2 (p=0.002 vs p=0.028, respectively). Triglyceride levels were significantly higher in group 1 patients (120.8+/-88.8 vs 100.5+/-58.5 mg/dl, p=0.044). In conclusion, ultrasonography is an easy and noninvasive method for the diagnosis of fatty liver in children with obesity. Body mass index and serum lipids were higher in group 1 patients. The diagnosis and early treatment of obesity in childhood is important for the prevention and better treatment of related complications. Thus, ultrasonography should be a part of the early evaluation of obese children.