Abstract: AIM:To observe the therapeutic effect of noninvasive mechanical ventilation on patients with acute left ventricular failure and the changes of Creactive protein (CRP). METHODS: A total of 53 patients with acute left heart failure were randomly divided into two groups: conventional group of 27 patients treated with highflow oxygen and routine drug therapy and noninvasive ventilation group of 26 cases treated with bilevel noninvasive positive pressure ventilation via face mask and routine drug therapy. Clinical efficacy and CRP levels in the two groups were assessed. RESULTS: The effective rates in noninvasive ventilation group and conventional group were, respectively, 96% and 70%, with statistically significant differences (P<005). Twentyfour hours after treatment, CRP levels were significantly lower than those before treatment (P<001) and the difference between the two groups was statistically significant (P<001). After treatment, systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and respiratory rate (RR) were significantly lower than those before treatment (P<001), whereas PaO2 and SPO2 increased (P<001). One hour after treatment, a statistically significant difference was observed in SBP, DBP, HR, RR, PaO2 and SPO2 between conventional group and noninvasive ventilation group (P<001 or 005). Twentyfour hours after treatment, a statistically significant difference was seen in PaO2 and SPO2 between groups (P<001). CONCLUSION: Noninvasive mechanical ventilation can improve the treatment efficacy in patients with acute left ventricular failure and reduce the level of CRP.