Background: Determination of Alanine aminotransferase serum levels ([ALT]) is a sensitive and reliable test for liver diseases. Aim: To report the prevalence of abnormal [ALT] sin Chilean population and to identify associated variables. Methods: We analyzed data from a random sub-sample of 2,794 adults surveyed during the second Chilean National Health Survey. Abnormal [ALT],were defined by using three different cut-off values (COV), two fixed COV (COV1: >30 IU/L in men and > 19 IU/L in women and COV2 pre-defined by the performing laboratory) and a COV adjusted by age, weight and sex (COV3 >31 IU/L for women and >44 IU/L and men > 42 IU/L and > 66 IU/L with a BMI > 23). Logistic regression analysis was performed to determine risk factors for elevated [ALT] Results: Mean [ALT], values were 30.14 IU/L in men and 22.03 IU/L in women. The observed prevalence of abnormal [ALT],defined by different COV were 38%, 11.5%, and 8.1% for COV1, COV2 and COV3 respectively. Variables independently associated to abnormal [ALT], in a multivariate analysis were the following: serum gamma-glutamyl-transpeptidase (OR:1.055 [95% CI 1.033-1.078]) and body mass index (OR:1.13 [95% Cl 1.091.17]). Variables inversely associated with abnormal [ALT],(COV1) were male gender (OR:0.976 [95% CI 0.96-0.99) and HDL-cholesterol (OR:0.979 [95% CI 0.96-0.99]). Conclusions: Independently of the COV used, Chilean population exhibits a high prevalence of abnormal [ALT],which may reflect a significant burden of liver disease. Non-alcoholic fatty liver disease could be a major contributor to elevated [ALT], considering the association of abnormal [ALT], and metabolic variables.