Objective To observe the serumlevel of neuron-specific enolase( NSE) in patients with pulmonary encephalopathy and its changes after treatment with mechanical ventilation. Methods Twentyone patients with pulmonary encephalopathy were enrolled. Glasgow coma scale( GCS) , serumNSE level, and arterial blood gas were evaluated at three time-points: before mechanical ventilation, after 12 hours mechanical ventilation, and the moment of consciousness. Results 18 patients recovered consciousness, and 3 patients remained in persistent coma and died. GCS and arterial blood gas improved obviously after 12 hours mechanical ventilation. Meanwhile, the serumNSE concentration decreased significantly after 12 hours mechanical ventilation [ ( 24. 54 ±6. 65) μg/L] and at the moment of consciousness [ ( 14. 19 ±2. 91) μg/L] compared with before mechanical ventilation( P lt; 0. 05, P lt; 0. 01) . Conclusion Dynamic measurment of serumNSE may be a useful biomarker for assessing the severity of cerebral injury and predicting prognosis.