Background and Objectives: Alanine aminotransferase (ALT) is generally used for evaluating liver function, and its concentrations are closely associated with sex and nutritional status. This study investigates the relation- ships between dietary components and serum ALT activity in Taiwanese adolescents. Methods and Study De- sign: Data were collected from 1,941 adolescents aged 13-18 years who participated in the fourth National Nutri- tion and Health Survey in Taiwan (2010-2011, adolescents). Results: The mean age was 15.3±0.1 y (15.3±0.1 y for boys and 15.2±0.1 y for girls). Mean serum ALT was 14.8±13.3 U/L (17.7±16.3 U/L for boys and 12.1±8.7 U/L for girls; p<0.001). Multivariate analysis revealed that, among girls, a single-unit increase in dietary zinc was associated with 1.12- and 1.11-fold increases in risk for increased serum ALT tertile 2 (T2) and T3, respectively, compared with T1; and a single-unit increase in vitamin B-2 intake increased risk by 1.71- and 1.54-fold, respec- tively. Further analysis revealed that the risk increase for boys and girls who consumed the highest amounts of dietary zinc and vitamin B-2 (T3) was 1.97- and 2.62-fold, respectively; they were also more likely to have high- er serum ALT (>11 U/L for boys and >9 U/L for girls) than those of the reference (presented as zinc T1 and vit- amin B-1 T1). Conclusions: Increased dietary zinc and vitamin B-2 intake is associated with higher serum ALT in adolescents.