Introduction: Obesity in childhood increases the risk of fatty liver disease. With respect to the increased prevalence of obesity in Iran and the world, this study aimed to investigate the relationship between fatty liver and obesity in 6 -18 year-old children.

Method: In this case-control study, 25 overweight children and 24 obese children, who had inclusion criteria, were selected by convenience sampling method. Then 27 children and teenagers with normal weight and the same sex and age were selected as the control group. Weight and height of the sparticipants were measured and recorded, liver enzymes ALT and AST were performed for them. Data was analyzed in SPSS software using chi-square test, one-way ANOVA, Tukey range follow-up, and logistic regression. The significant level was set at p<0.05.

Results: The results showed that the relative frequency of occurrence of fatty liver increased significantly along with increasing body mass index (p<0.001). There was a significant relationship between sex, body mass index, and the prevalence of fatty liver in the participants. However, no significant relationship was found between fatty liver disease and AST and ALT (p>0.05).

Conclusion: There was a strong relationship between NAFLD and the abnormal body mass  in children. It will be very useful if obese  children to screen for susceptible to NAFLD