Abstract: To explore the mechanism of multiple organ dysfunction and consenescence in patients with obstructive sleep apnea syndrome(OSAS) by observing the levels of SOD, GSHPX and MDA after threemonth treatment of continuous positive airway pressure (CPAP). Methods: The contents of SOD,GSHPX and MDA were detected in 63 patients with OSAS before and after threemonth CPAP treatment and compared the results from 60 healthy controls. Results: The contents of SOD, GSHPX and MDA were 139.6±36.6 nmol/L, 78.6±8.0 U/ml and 1.48±0.59 mmol/L respectively in the healthy people, 104.5±39.3 nmol/L, 61.5±6.7 U/ml and 5.87±1.67 mmol/L respectively in patients with OSAS, and 134.5±36.1 nmol/L, 74.6±6.6 U/ml and 1.62±0.58 mmol/L in patients with OSAS after threemonth CPAP treatment. The level of MDA was higher in patients with OSAS than in the healthy people（P＜0.05）. The levels of SOD and GSHPX were lower in patients with OSAS than in the healthy people（P＜0.01）, but three months after CPAP treatment,　they were not significantly different with those of the healthy people （P＞0.05）.　Conclusion: The levels of the oxygen free radicals are imbalance in the patients with OSAS, which probably is an important reason for the multiple organ dysfunction,and this can get well after threemonth CPAP treatment.

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