BACKGROUND: Initial treatment of chronic idiopathic thrombocytopenic purpura (ITP) is generally done with corticosteroid. In case of refractory to corticosteroid or dependency, splenectomy seems to be the most effective and definitive treatment. Partial splenic embolization is an easier procedure with minimal morbidity. We evaluated the efficacy and complications of partial splenic embolization as treatment of chronic ITP refractory to corticosteroid or corticosteroid dependency. METHODS: Eight patients with chronic ITP and two systemic lupus erythematosus (SLE) patients with immunothrombocytopenia underwent partial splenic embolization. Embolization of 70~80% of the splenic volume was performed with endocoils or gelform particles without anesthesia by selective arterial catheterization and followed up for 4~50 months. The therapeutic effect of partial splenic embolzation was defined on the basis of the platelet count at the last follow-up after partial splenic embolzation : complete response, >100,000/nL,partial response, 100,000~50,000/nL and no response, <50,000/nL without medication. RESULTS: Partial splenic embolization brought a complete response in six of ten patients, a partial response in three, and no response in one. With a follow-up of 4~50 months, these responses were maintained in all except three patients. One patient was treated by splenectomy and one by partial splenic embolization again. Tolerance was good in all patients. Abdominal pain and fever was observed in 8 and 4 patients, respectively. One patient had a left pleural effusion with spontaneous resolution. No serious infection occurred. All patients were discharged within 6 days after partial splenic embolization. CONCLUSION: We conclude that partial splenic embolization may be useful and safe procedure and a good alternative to splenectomy in chronic ITP refractory to medical treatment.