Objective: Since the role of fibrinolytic activity is unclear in coronary artery ectasia, we investigated the entire fibrinolytic activity by a new test, global fibrinolytic capacity (GFC) in the ectasia patients. Methods and results: Thirty-four ectasia patients (18 male, mean age: 58 +/- 8 years) presenting with acute coronary syndrome and 25 controls (14 male, mean age: 56 +/- 9 years) with normal coronary artery were evaluated. GFC, D-dimer and other hemostatic factors were assessed. Clinical characteristics were comparable in both groups. Serum GFC (4.6 +/- 2.1 vs. 3.1 +/- 2.1 mug/ml, p = 0.03) and D-dimer levels (0.69 +/- 0.42 vs. 0.41 +/- 0.38 ng/ml, p = 0.02, respectively) were significantly higher in ectasia patients than in controls. They were also higher in subgroup of patients with myocardial infarction (four patients) compared with other ectasia patients and controls (p = 0.04, 0.01, respectively). Other hemostatic factors were not different in both groups. GFC was correlated with D-dimer (r = 0.76, p = 0.01). Conclusion: Our results suggest that fibrinolytic system activation may develop in ectasia patients with acute coronary syndrome. It can be induced by thrombus formation in ectatic segment of coronary artery.