Cepharanthine (CEP), an alkaloid drug that has a cell membrane stabilizing effect and an immunomodulating effect, has been reported to improve symptoms and signs of chronic immune thrombocytopenia (ITP). In this study, we retrospectively assessed the clinical efficacy and adverse events of high-dose CEP for 47 patients with ITP. The response rate (elevation of platelet count>5×10(4)/μl) was 44%, and CEP treatment was judged useful in clinical aspects by their attending doctors in 77% of the cases. Next, we made a comparative analysis between patients who were administered CEP as a single agent (22 patients) and those administered CEP in combination therapy with prednisolone (PSL) (20 patients). There was a marked increase in platelet count in both groups compared to the count before CEP treatment (P<0.01), and no significant difference was seen between the two groups. High-dose CEP was well tolerated, and in some patients single-agent CEP therapy resulted in a significant elevation of platelets, allowing a reduced dosage of PSL.