Aim To investigate the prognosis and its risk factors in young adults （less than 45 years old） with acute myocardial infarction （AMI）. Methods Continuous AMI cases （less than 45 years old） were retrospectively collected in department of cardiology of the first affiliated hospital of Soochow University from January 2007 to December 2013. Poor prognosis was confirmed if there was any major adverse cardiac event （MACE） including cardiac death, cardiac arrest, acute heart failure, recurrent myocardial infarction during the period from onset to follow-up. The risk factors were analyzed by univariate and multivariate logistic regression analysis. Results 118 continuous cases were collected, 4 of which were excluded, and 5 cases were lost. The remaining 109 patients were analyzed. Among them, the mean age was 41.0±7.0 years old, 89.0% were males, and the mean follow-up period was 27 months. Two factors including percutaneous coronary intervention （PCI）（OR0.061, 95%CI 0.008～0.474, P0.007）, admission heart rate（OR1.084, 95%CI 1.029～1.143, P0.002） entered the regression equation. Conclusions Without undergoing PCI and higher admission heart rate are the independent risk factors for prognosis in young adults with AMI.