Obese children have increaed in Korean in recent years as socieconomic status have got more higher than past years. Obese children have many health problems and some kinds of complications. Obese patients who have fatty liver with abnormal liver function should be managed with weight control. This study was intended to investigate the effect of weight control on hepatic abnormalities of obese children with fatty liver. We managed 6 obese children who had fatty liver with abnormal liver finction for weight control containing behavior modification, diet and exercise during 3 months. After 3 months, we compared body weight, liver function test, dietary intake and exercise. Body mass index(BMI) showed significant decrease from 28.1$pm$2.3kg/$m^2$ to 26.2$pm$1.7kg/$m^2$ (p<0.01). Aspartate aminotransferase(AST) showed significant improvement from 56$pm$15IU/l(p<0.01). Alanine aminotransferase(ALT) also showed significant improvement from 108$pm$38IU/l to 33$pm$9IU/l(p<0.01). Therefore if we can rule out the other causes of hepatic abnormalities in obese children with fatty liver, these patients showed benefit by weight control as it can improve both obesity and liver functions.