The correlation between plasma D-dimer level and reperfusion has not been clarified yet in thrombolytic therapy applied for acute myocardial infarction patients. The aim of this study was to investigate whether there is a relationship between reperfusion and fibrinolytic activity in acute myocardial infarction patients treated with thrombolytic therapy. Fibrinolytic activity was reflected by plasma D-dimer levels. During the study period, 186 patients were initially analyzed. But 18 of these patients were excluded from the study because they were not suitable for study criteria. Blood was collected from 168 acute myocardial infarction patients within first 6 h. Intravenous tissue plasminogen activator (100 mg) or streptokinase (1,500,000 U) was applied to patients. Mean age of the patients was 58 (28-86) years and majority was men (86%). The number of anterior, inferior, and lateral myocardial infarction patients were 76 (45.2%), 85 (50.6%), and seven (4.2%), respectively. The mean time from symptom onset to thrombolytic application was 134 (95-212) min. Reperfusion occurred in 115 (68.5%) patients. D-dimer levels were markedly high after thrombolytic therapy versus before (155 mg/dl, 362 mg/dl, P<0.005). We compared the D-dimer values before and after thrombolytic therapy between reperfused group and the nonreperfused group (189-409 mg/l in reperfused group, P=0.086; 82-258 mg/l in the nonreperfused group, P=0.173). In conclusion, in this study, D-dimer levels were elevated markedly in patients with ST elevation myocardial infarction after thrombolytic therapy, but no significant difference was seen in D-dimer levels between the reperfused and nonreperfused groups.