We assessed the association between serum gamma glutamyl transferase (GGT) activity with postprimary percutaneous coronary intervention (PCI) coronary flow and in-hospital major advanced cardiac events (MACEs) in patients with ST elevation myocardial infarction (STEMI). Patients with STEMI (n = 425; males 78%; mean age 60 +/- 13 years) were enrolled. Patients were divided into 3 GGT tertiles and 2 groups according to thrombolysis in myocardial infarction (TIMI) flow grade. The TIMI flow percentages were similar in the 3 GGT tertiles (32%, 45%, and 42%, respectively, P = .336). Total MACE increased with GGT tertiles (among tertiles, respectively; P < .001). The total MACE was significantly higher in impaired flow group than in normal flow group (23% vs 7%; P < .001). At multivariate analyses, serum GGT activity was an independent predictor of in-hospital MACE (odds ratio [OR] 1.12, 95% confidence interval [CI] 1.01-1.33; P < .001). In conclusion, serum GGT activity is associated with in-hospital MACE in patients with STEMI undergoing primary PCI.