Except for patients with underlying myeloproliferative diseases (MPD), thrombocytosis is rarely encountered in cirrhotic patients after liver transplantation. Although the long-term control of primary thrombocytosis is important for the prevention of graft thrombosis in MPD patients, the threshold for intervention and best mode for the control of persistent reactive thrombocytosis after liver transplantation is unclear. We present two patients with extreme reactive thrombocytosis (over 1,000 x 10(9)/l) due to intra-abdominal sepsis after liver transplantation. Furthermore, both patients suffered from bleeding problems as well as ongoing venous thrombosis of the graft. Rapid control of the platelet count was achieved using platelet apheresis. The use of cell separation procedures may be a relatively rapid, reversible, and reasonably safe way to control platelet counts peri-operatively in liver transplant recipients. (C)2004 Wiley-Liss. Inc.