Thrombotic thrombocytopenic purpura is a serious, potentially fatal disease, and conventional plasma exchange appears to be the best initial therapy. Following this approach, survival in 90% of patients is available. In patients with relapse and treatment failure to plasma exchange, splenectomy is recommended. The rationale for splenectomy and the relevant pathomechanisms involved are obscure. In the present paper two patients with TTP are reported who first responded to conventional treatment strategies but later relapsed. Resumption of previous therapy was not able to continuously maintain normal platelet levels. Thus, splenectomy was considered to be indicated. In contrast to former reports, repeated cycles of conventional plasma exchanges were performed until a transient steady state (12 hrs) of the platelet counts occurred. Then splenectomy was performed immediately and, in contrast to former reports, no reinstitution of treatment was necessary after splenectomy. In addition no postoperative complications (bleeding, neurologic impairment) have been observed. This favorable outcome might be due to the strategy of repeated conventional plasma exchange procedures. The follow-up shows now event free disease for 2 years.