It is considered that percutaneous cardiopulmonary support (PCPS)-associated thrombosis is rare on antithrombotic coated PCPS if anticoagulation therapy is appropriately performed. We experienced two cases in which the association between antithrombotic coated PCPS and venous thrombus formation was highly suspected. These cases suggest that PCPS-associated venous thrombus formation should be checked frequently during and after PCPS even if anticoagulation was appropriately performed.