Objective To investigate the effect of plasma exchange with non- bioartificial liver support system on serum manganese levels in patients with hepatic encephalopathy and its clinical significance. Methods A total of 22 inpatients with hepatic encephalopathy who were admitted to our hospital from October 2007 to July 2011 were treated with plasma exchange,and were divided into improvement group and aggravation group based on prognosis. The serum manganese level was dynamically determined using graphite furnace atomic absorption spectrophotometry,and the changes in manganese levels after treatment and relief or worsening of disease were analyzed. Comparison between the two groups was made using t test. Results After treatment,the 22 patients all showed significantly reduced manganese levels( 22. 6 ± 6. 9μg /L vs 36. 4 ± 10. 6 μg /L,t = 4. 789,P = 0. 000). After treatment,8 cases improved and 14 cases aggravated,and the improvement group showed a significantly lower manganese level than the aggravation group( 18. 9 ± 6. 3 μg / L vs 39. 2 ± 9. 8 μg / L,t = 4. 816,P =0. 000). Conclusion Non- bioartificial liver support system can reduce serum manganese levels in patients with hepatic encephalopathy,and the serum manganese level may influence the disease progression.