Objective To study the effect of noninvasive positive pressure ventilation (NPPV) in chronic obstructive pulmonary disease (COPD) patients with hypercapnic coma secondary to respiratory failure.Methods COPD patients with or without coma secondary to respiratory failure were both treated by bi-level positive airway pressure (BiPAP) ventilation on base of routine therapy.There were 32 cases in coma group and 42 cases in non-coma group.Such parameters as arterial blood gas (ABG)，Glasgow coma scale (GCS)，time of NPPV therapy，achievement ratio，and adverse effects were investigated.Results 30 patients in the coma group were improved after NPPV treatment (26 cases recovered consciousness treated by BiPAP in 2 hours，3 cases recovered between 3~8 hours，1 case recovered after 24 hours).The parameters of ABG，the tidal volume and the minute ventilation volume were improved after BiPAP.The time of effective therapy was (9±4) days in the coma group and (7±3) days in the non-coma group with no significant difference (Pgt;0.05).The achievement ratio was similar in two groups (93.75% vs 97.62%，Pgt;0.05).But the incidence of gastrointestinal tympanites reached to a higher level in the coma group (80.5%) than the non-coma group (10.6%).Conclusion COPD patients with hypercapnic coma secondary to respiratory failure isn’t the absolute contraindication of NPPV treatment.