Objective:To investigate the effect of early mechanical ventilation on mortality of patients with severe acute left ventricular failure.Methods:Ninety patients with acute left ventricular failure were divided into early mechanical ventilation group (n=45) and conventional mechanical ventilation group (n=45).Time of symptomatic relief,duration of mechanical ventilation and the mortality on 7 days were observed.Results:There was no difference in time of symptomatic relief between the two groups (4.7±1.7h vs 5.0±1.8h,P0.05);but the duration of mechanical ventilation was significantly shorter in the early mechanical ventilation group than that in conventional mechanical ventilation group (15.6±4.5h vs 33.1±13.4h,P0.01);and the mortality on 7 days was significantly lower than that in conventional mechanical ventilation group (8.9% vs 26.7%,P0.05).Conclusion:Early mechanical ventilation can decrease the mortality of patients with severe acute left ventricular failure.