Objective To investigate the short- and long-term therapeutic efficacies of intravenous transplantation of bone marrow stem cells(MSCs) in rats with experimental myocardial infarction by metaanalysis.Methods Randomized controlled trials were systematically searched from Pub Med,Science Citation Index(SCI),Chinese journal full-text database(CJFD) up to December 2014.While the experimental groups(MSCs groups) were injected MSCs intravenously,the control groups were injected Delubecco’s minimum essential medium(DMEM) or phosphate buffered saline(PBS).Subgroup analysis for each outcome measure was performed for the observing time point after the transplantation of MSCs.Weighted mean differences(WMD) and 95% confidence intervals(CI) were calculated for outcome parameters including ejection fraction(EF) and fractional shortening(FS),which were measured by echocardiogram after intravenous injection and analyzed by Rev Man 5.2 and STATA 12.0.Results Data from 9 studies(190 rats) were included in the meta-analysis.As compared to the control groups,the cardiac function of the experimental groups were not improved at day 7(EF:WMD=0.08,95%CI-1.32 to 1.16,P>0.01; FS:WMD=-0.12,95%CI-0.90 to 0.65,P>0.01) until at day 14 after MSCs’ transplantation(EF:WMD=10.79,95%CI 9.16 to 12.42,P<0.01; FS:WMD=11.34,95%CI 10.44 to 12.23,P<0.01),and it lasted 4 weeks or more after transplantation of MSCs(EF:WMD=13.94,95%CI 12.24 to 15.64,P<0.01; FS:WMD=9.64,95%CI 7.98 to 11.31,P<0.01).Conclusion The therapeutic efficacies of MSCs in rats with myocardid infarction become increasing apparent as time advances since 2 weeks after injection. Objective To investigate the short- and long-term therapeutic efficacies of intravenous transplantation of bone marrow stem cells (MSCs) in rats with experimental myocardial infarction by metaanalysis. Methods Randomized controlled trials were systematically searched from Pub Med, Science Citation Index (SCI), Chinese journal full-text database (CJFD) up to December 2014. Whilst the experimental groups (MSCs groups) were injected intravenously into MSCs intravenously, the control groups were injected Delubecco’s minimum essential medium (DMEM) or phosphate buffered saline (PBS) each outcome measure was performed for the observing time point after the transplantation of MSCs.Weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated for outcome parameters including ejection fraction (EF) and fractional shortening (FS), which were measured by echocardiogram after intravenous injection and analyzed by Rev Man 5.2 and STATA 12.0. Results Data from 9 studies (190 rats) were included in the meta-analysis. As compared to the control groups, the cardiac function of the experimental groups were not improved at day 7 (EF: WMD = 0.08, 95% CI- 1.32 to 1.16, P> 0.01; FS: WMD = 0.12, 95% CI-0.90 to 0.65, P> 0.01) until after day 14 after MSCs transplantation (EF: WMD = 10.79, 95% CI 9.16 to 12.42, P <0.01; FS: WMD = 11.34, 95% CI 10.44 (EF: WMD = 13.94, 95% CI 12.24 to 15.64, P <0.01; FS: WMD = 9.64, 95% CI 7.98 to 11.31, P <0.01), and lasted 4 weeks or more after transplantation of MSCs P <0.01) .Conclusion Therapeutic efficacies of MSCs in rats with myocardid infarction become increasing as time as since 2 weeks after injection.