Objective To observe the effect of plasma exchange (PE) on patients with thrombotic throbocytopenic purpura (TTP) . Methods Eight patients received PE and drugs treatment (including glucocorticoid and anti-platelet drugs) . The other 7 patients were only treated with glucocorticoid and anti-platelet drugs. PE was performed with fresh-frozen plasma every other day, and median of PE treatment was 4 times(2 to 6 times) . Average exchanged volume of plasma was (2316?28. 3) ml. Results The survival rate of the patients with PE treatment was significantly higher than that of the patients only with drugs (75% vs 14. 3% ) . Within 12-72 h after the plasma treatment, neurological and psychiatric symptoms ameliorated. After 4 times of PE treatment, hematocrit and platelet increased gradually, and fever, novel petechia, purpura and jaundice were not observed again in the survival patients. When the PE treatment finished, 2 cases relapsed and received PE treatment again. Conclusion PE is an effective therapy for TTP.