Aim: As obesity rates in children and adolescents increase, non-alcoholic fatty liver disease (NAFLD) has become the most common liver disease affecting this organ.This study aimed to evaluate the effectiveness of lifestyle modifications as a method of improving liver function indexes in children with NAFLD. Materials and Methods:The study group consisted of 49 patients with NAFLD (35 boys and 14 girls), age range 3-16 years (mean 10.51±3.18years).Anthropometric measurements were taken and laboratory tests were performed.Features of steatosis of the liver were evaluated by ultrasound.The mean follow-up period was 2.45±1.45years.Aspartate aminotransferase (AST) to [Platelet (PLT) Ratio and Pediatric NAFLD Fibrosis Score (PNFS)] were calculated.The Mediterranean diet and physical exercises were recommended.End-point parameters were a decrease in the aminotransferase level and body weight.Results: In the study group, 35 children (71.43%) were obese, and 7 (14.29%)were overweight.In 22/49 cases (44.9%) body mass index (BMI) loss was achieved, in the other patients, BMI gain was noted.Abnormal alanine aminotransferase (ALT) levels were observed in 25/49 children.In the group of children with initial increased ALT levels, significant reduction of ALT, AST and gamma-glutamyltransferase (GGT) levels were found with regard to baseline values.There was also a significant decline in mean AST to PLT Ratio index (APRI) level and PLT count.Moreover, a decrease in ALT level was negatively related to PNFS, APRI and GGT. Conclusion:Lifestyle modification leads to a significant decrease in aminotransferase levels, even in children who fail to achieve BMI reduction.