Abstract: AIM:To investigate the impact of repetitive balloon dilatations on slow/no-reflow and short-term prognosis in patients with ST-elevation acute myocardial infarction (STEAMI). METHODS: Two hundred and seventy-eight consecutive AMI patients treated with primary percutaneous coronary intervention (PCI) within 12 h of symptom onset were divided into repetitive dilatation group (n=124) and nonrepetitive dilatation group (n=154). Each group was further divided into two subgroups according to the degree of thrombus burden. RESULTS: Repetitive balloon dilatation was present in 124 patients (44.6%) with no significant differences between groups in post-stent TIMI grade flow, infarction related artery (IRA) and thrombus burden. Compared with the repetitive dilatation in patients with low thrombus burden, repetitive dilatation in patients with high thrombus burden had a significantly lower rate of postrevascularization (TIMI grade III flow: 64% vs. 90%; P<0.01) and higher peak CK-MB values (286±166 vs. 460±202, P<0.05) and rate of MACE (12% vs. 2%, P=0.01). CONCLUSION: Repetitive balloon dilatation after stent implantation is related to short-term prognosis, myonecrosis and angiographic slow/no reflow of IRA in high-thrombus burden patients with STEAMI.