Vitamin D deficiency is one of the most prevalent disease in the world. Recently, there have been many studies on vitamin D deficiency and some have focused on the association between vitamin D and nonalcoholic fatty liver disease (NAFLD). Therefore, the objective of this study is to assess the relationship between vitamin D deficiency and fatty liver disease in adolescents based on the Korean surveys. In this cross-sectional study, the relationship between vitamin D and aminotransaminase (ALT) was investigated based on the Korean National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2014 with adolescents at the age of 12-18. Vitamin D deficiency was defined as serum 25-hydroxy vitamin D (25(OH)D) level below 20ng/mL and serum ALT level above 30U/L was classified as suspected NAFLD. A total of 3852 adolescents were included in the study. Among them, 53% of them were male, 77% showed Vitamin D deficiency while 5.2% were found to have suspected NAFLD. The mean vitamin D level was significantly lower in suspected NAFLD group compared to the control(15.42 ± 4.5ng/mL vs 16.41 ± 5.3 ng/mL, P 0.01). Suspected NAFLD was also associated with age, gender, overweight, waist circumference, fasting blood glucose, systolic blood pressure (SBP), serum lipid and insulin level. After adjustment for age, gender, SBP, fasting blood glucose and BMI in multivariate regression logistic analysis, Vitamin D levels (OR 1.04, 95%CI, 1.006-1.075) were inversely associated with suspected NAFLD. Vitamin D levels are inversely associated with suspected NAFLD in adolescent, even after adjusting for obesity.