Objective This study explored the correlation of longitudinal changes in serum alanine aminotransferase(ALT) and aspartate aminotransferase(AST) levels with the incidence of metabolic syndrome(Mets) based on a dynamic health examination cohort. Methods A Mets-free dynamic cohort involving 4541 participants who underwent at least three health examinations from 2006 to 2011 was included in the study. Mets was defined according to the Chinese Medical Association Diabetes Branch definition that included hypertension, obesity, hyperlipidemia, and hyperglycemia. Generalized estimating equation(GEE) model was used to analyze multivariate relative risk(RR) of repeated observations of ALT and AST in quartiles for Mets or its components according to gender. Results In all, 826 Mets cases were reported. Adjustment of relevant parameters indicated that time-varying changes in ALT and AST levels were positively associated with the incidence of Mets in a dose-response manner. Positive association between high ALT levels and fatty liver was much stronger than that between high AST levels and fatty liver, particularly in male participants. These associations were consistently observed in the following subgroups: participants with ALT and AST levels of <40 U/L, participants with of <25 kg/m2, and participants with non-fatty liver. Furthermore, participants with 2 Mets components at baseline showed lower multivariate adjusted RRs of ALT and AST for Mets than participants with 0-1 Mets component. Conclusion These results suggested that elevated serum ALT and AST levels were early biomarkers of Mets or its components. Objective This study explored the correlation of longitudinal changes in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels with the incidence of metabolic syndrome (Mets) based on a dynamic health examination cohort. Methods A Mets-free dynamic cohort involving 4541 participants who underwent at least three health examinations from 2006 to 2011 was included in the study. Mets was defined according to the Chinese Medical Association Diabetes Branch definition that includes hypertension, obesity, hyperlipidemia, and hyperglycemia. Generalized estimating equation (GEE) model was used to analyze of multivariate relative risk (RR) of repeated observations of ALT and AST in quartiles for Mets or its components according to gender. Results In all, 826 Mets cases were reported. Adjustment of relevant parameters indicated that time-varying changes in ALT and AST levels were positively associated be with the incidence of Mets in a dose-response manner tween high ALT levels and fatty liver was much stronger than that between high between AST levels and fatty liver, particularly in male participants. These associations were consistently observed in the following subgroups: participants with ALT and AST levels of <40 U / L, participants with of <25 kg / m2, and participants with non-fatty liver. Further, participants with 2 Mets components at baseline showed lower multivariate adjusted RRs of ALT and AST for Mets than participants with 0-1 Mets component. serum ALT and AST levels were early biomarkers of Mets or its components.