We found that of 1,192 patients who underwent primary percutaneous coronary intervention and who had final Thrombolysis In Myocardial Infarction grade 3 flow at the conclusion of the procedure, transient no-reflow occurred in 16 patients (1.3%). Compared with patients without transient no-reflow during the procedure, those with transient no-reflow had higher in-hospital (2% vs 13%, p=0.04) and 6-month mortality (3% vs 31%, adjusted odds ratio 5.4, 95% confidence interval 1.01 to 29.0, p=0.0001).