ObjectiveTo systematically review the efficacy and safety of early oxygen therapy for patients with acute myocardial infarction (AMI). MethodsWe searched databases including PubMed, EMbase, The Cochrane Library (Issue 11, 2015) and CBM from inception to October 2015, to collect randomized controlled trials (RCTs) about early oxygen therapy for patients with AMI. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed by using RevMan 5.3 software. ResultsA total of 7 RCTs involving 1 388 patients were included. The results of meta-analysis showed that, there were no significant differences between the oxygen therapy group and the control group in mortality (OR=1.12, 95%CI 0.57 to 2.20, P=0.75), the incidence of major cardiovascular and cerebrovascular events (MACCE) (OR=1.00, 95%CI 0.46 to 2.18, P=1.00), the incidence of arrhythmia (OR=1.01, 95%CI 0.45 to 2.24, P=0.98) and the incidence of cardiac death (OR=0.53, 95%CI 0.17 to 1.67, P=0.28). But, the oxygen therapy group had higher risk of recurrent myocardial infarction (OR=5.50, 95%CI 1.44 to 20.99, P=0.01) and longer average hospital length of stay (MD=1.28, 95%CI 1.10 to 1.47, P<0.0001). ConclusionThe efficacy of early oxygen therapy for patients with AMI is not clear, even may increase the risk of recurrent myocardial infarction and the average hospital length of stay. Due to the limited quantity and quality of include studies, more high quality studies are needed to verify the above conclusion.