Abstract: Objective To evaluate the effects of extracorporeal membrane oxygenation (ECMO) on mortality in adult patients with acute respiratory distress syndrome (ARDS).Methods Literature concerning randomized controlled trials (RCTs),case-control studies and prospective cohort studies from January 1966 to July 2011 on ECMO for the treatment of ARDS patients was retrieved by electronic and manual search.Meta-analysis of the use of ECMO in the treatment of ARDS patients was conducted using the methods recommended by the Cochrane Collaboration's software RevMan 5.0.Results Three papers reporting RCTs and 6 papers concerning observational cohort studies of using ECMO in patients with severe ARDS were enrolled for analysis.Meta-analysis of the 3 RCTs (310 patients,159of them treated with ECMO) revealed ECMO did not decrease the mortality of ARDS patients [ odds ratio (OR)=0.75,95% confidence interval (95% CI) 0.45-1.24,P=0.27 ].Meta-analysis of the all 9 studies (1058 patients,386 of them treated with ECMO ) revealed ECMO increased the mortality of ARDS patients (OR=1.58,95%CI 0.94-2.67,P=0.08).Conclusion There is no evidence to prove that ECMO is beneficial in adult patients with ARDS,therefore further investigation with a large sample of high quality RCT is warranted.