Objective To evaluate the efficacy of noninvasive positive-pressure ventilation (NPPV) on acute respiratory failure (ARF) in elderly patients with severe community-acquired pneumonia (CAP).Methods 321 CAP patients with ARF aged over 65 years [(75.6±12.2) years old in averag] were randomly treated with NPPV (n=162) and the standard oxygen therapy (n=159).Intubation rate,ARF control rate and total mortality were compared between the two groups,and the risk factors were analyzed.Results 90％ of 321 patients presented with hypoxemic respiratory failure.Compared with standard therapy group,the intubation rate was lower in NPPV group (46.9％ vs.64.2％,x2=9.652,P＜0.01).However,there were no differences in ARF control rate(77.9％ vs.72.3％,x2 =1.274,P＞0.05),overall 30-day mortality and 90-day survival between the two groups.The overall mortality in NPPV group was higher in treatment failure cases than in treatment success cases (48.7％ vs.11.6％,x2=26.900,P＜0.01).The independent risk factors for death were treatment failure in NPPV,higher simplified acute physiology score assessment,old age and mutilobar infiltrate.Conclusions NPPV can decrease the intubation rate in CAP patients with acute hypoxemic respiratory failure,but the overall efficacy is not significant.Delayed intubation should be avoided when NPPV is to be applicated.