Serum γ-glutamyl transferase (GGT) activity is a risk predictor for the development of coronary artery disease and is related to cardiovascular morbidity and mortality. We evaluated the clinical utility of GGT activity in predicting high troponin levels in patients with acute coronary syndrome (ACS) admitted to the emergency department with chest pain. A total of 200 troponin-positive and 203 troponin-negative patients were classified into groups 1 and 2, respectively. γ-Glutamyl transferase activity was significantly higher in group 1 (44 ± 34 U/L) compared with group 2 (31 ± 26 U/L, P = .001). A GGT activity cutoff >25.5 showed 62% sensitivity and 61% specificity in predicting troponin positivity. Logistic regression analysis demonstrated a significant predictive value of GGT for troponin positivity. Spearman rank correlation analysis showed a moderately strong relationship between GGT activity and troponin positivity. Considering the predictive value of high GGT activity for troponin positivity, GGT activity may complement other diagnostic biomarkers for predicting troponin positivity in patients having ACS admitted with chest pain.