Background: Results of studies comparing direct stenting (DS) with conventional stenting (CS) after balloon predilatation in patients with acute myocardial infarction (MI) have been reported in the past, however they are conflicting. There are only few randomised studies that aim to answer whether DS improves epicardial and myocardial patency. Aim: To assess the effects of DS on epicardial and myocardial patency in patients with acute MI. Methods: Consecutive patients with acute MI were randomised either to DS or CS strategy. Clinical exclusion criteria were as follows: clinical and electrocardiographic features of reperfusion, pulmonary oedema, cardiogenic shock, contradictions to coronarography, allergy to aspirin, ticlopidine, clopidogrel, heparin and stainless steel. Angiographic exclusion criteria were as follows: lesion <50% with correct patency in the infarct-related artery (IRA), lesion in the left main coronary artery, previously performed percutaneous coronary intervention in the target vessel, diameter of the IRA <2 mm or >4 mm. We assessed epicardial patency according to the TIMI (thrombolysis in myocardial infarction) scale and myocardial patency according to the TMPG (TIMI myocardial perfusion grade) scale. In addition, we analysed ST segment resolution in 12-lead electrocardiography (ECG). The ECG was performed before and 30 minutes after PCI. Results: We analysed 300 consecutive patients with acute ST segment elevation MI. After exclusion of patients not suitable for the study design, the DS group comprised 110 patients and the CS group – 107 patients. Clinical and angiographic results were similar in both groups. Initial TIMI 0 (48.2% vs. 43.0%), initial TIMI 3 (31.8% vs. 28.0%), initial TMPG 0-1 (77.3% vs. 78.5%), final TIMI 3 (95.5% vs. 93.5%) and final TMPG 2-3 (68.2% vs. 60.8%) were similar in the DS and CS groups, respectively (p=NS). The incidence of no-reflow phenomenon was comparable in both groups (4.5% vs. 6.5%, NS). The inclusive rate of no-reflow phenomenon plus worsening patency in the IRA were 6.4% vs. 10.3% in the DS and CS groups respectively. The ST segment resolution ł50% was 58.1% in the DS group and 56.1% in the CS group (NS). Conclusions: Direct stenting does not significantly improve epicardial and myocardial patency in an unselected group of patients with acute ST segment elevation MI.