AIM:To evaluate the prevalence and clinical characteristics of Nonalcoholic fatty liver disease(NAFLD) among asymptomatic Brazilian adolescents. METHODS:Transversal observational study included asymptomatic adolescents with central obesity from private and public schools in Salvador-Bahia,northeastern Brazil.The children answered a questionnaire that included age,gender,race,and medical history,and were submitted to a complete physical exam and abdominal ultrasound.Biochemical exams included:ALT,AST,GGT,C reactive protein(CRP),fasting glucose,insulin,cholesterol and triglycerides.Criteria for NAFLD included:the presence of steatosis in ultrasound and/or high level of ALT,negative or occasional historic of intake of alcohol(≤140 g/wk),negative investigation for hepatitis A,B,C,auto-immune hepatitis,Wilson disease and hemochromatosis.RESULTS:From October,2005 to October,2006,the study included 1801 subjects between 11 and 18 years of age and a mean age of 13.7±2.0 years.One hundred ninety-nine had central obesity.The prevalence of NAFLD was 2.3%,most of whom were male and white.Insulin resistance(IR)was observed in 22.9% of them and had positive correlations with ALT and GGT(P<0.05).Elevated CRP was observed in 6.9% of the cases;however,it was not associated with WC,IR or liver enzymes. CONCLUSION:The prevalence of NAFLD in Brazilian adolescents was low.The ethnicity may have influence this frequency in the population studied,which had a large proportion of African descendents. METHODS: Transversal observational study included asymptomatic adolescents with central obesity from private and public schools in Salvador-Bahia, northeastern Brazil. Children’s a questionnaire that includes age, gender, race, and medical history, and were submitted to a complete physical exam and abdominal ultrasound. Biochemical exams included: ALT, AST, GGT, C reactive protein (CRP), fasting glucose, insulin, cholesterol and triglycerides .Criteria for NAFLD included: the presence of steatosis in ultrasound and / or high level of ALT, negative or occasional historic of intake of alcohol (≤140 g / wk), negative investigation for hepatitis A, B, C, auto-immune hepatitis , Wilson disease and hemochromatosis .RESULTS: From October, 2005 to October, 2006, the study included 1801 subjects between 11 and 18 years of age and a mean age of 13.7 ± 2.0 years.One hundred ni nety-nine had central obesity.The prevalence of NAFLD was 2.3%, most of whom were male and white. Insulin resistance (IR) was observed in 22.9% of them and had positive correlations with ALT and GGT (P <0.05). Elevated CRP was observed in 6.9% of the cases; however, it was not associated with WC, IR or liver enzymes. CONCLUSION: The prevalence of NAFLD in Brazilian adolescents was low. Ethnicity may have influence this frequency in the population studied, which had a large proportion of African descendents.