The resistance to thrombolytic agents and delays in reperfusion occur in more than 30% after acute myocardial infarction. This may play an important role in the unsuccessful recanalization after thrombolytic therapy. The aim of this study is to assess the clinical and biochemical markers of reperfusion after different types of thrombolytic therapy and to find out the relationship between PAI-1 and ACE serum levels and the short-term outcome. Pretreatment ACE and PAI-1 plasma levels of 184 patients with acute myocardial infarction, treated with thrombolytic therapy were determined. Failure of thrombolysis was considered when reperfusion was delayed as assessed by noninvasive reperfusion criteria, reinfarction, and impaired left ventricular function. High plasma level of ACE (> 50 U/L), PAI-1 (> 43 ng/ml) and both was found in 57, 108 and 32 patients respectively. Subjects with high ACE plasma levels were characterized by impaired LV systolic function (79.0% vs. 75.0%), new Q-wave (88.4% vs. 74.2%), less reperfusion arrhythmia (19.3% vs. 22.8%) and prolonged hospitalization (70% vs. 66%) but no statistical significance was observed. High enzymes levels of PAI-1 were observed with higher incidence of anterior myocardial infarction (50.0% vs. 41.0%), lesser ST segment resolution (65.6% vs. 58.8%), reinfarction (6.3% vs. 5.9%), and impaired LV systolic function (90.6% vs. 76.0%), and prolonged hospitalization (70.4% vs. 63.4). There was a statistically significant difference between thrombolytic agents in the presence of high ACE regarding hospital overstay (p = 0.02). While the presence of high PAI-1 was significantly affect the degree of ST-segment resolution (p = 0.03).