Using a custom-made PVC medical tube ateriovenous (A-V) shunt and a porous polysulfone (PSf) catheter, an ex vivo and in vivo experiment were carried out to study the effectiveness of saline solution perfusion to prevent adhesion of platelets without using anticoagulants. The critical perfusion rate for preventing adhesion of platelets onto the PSf catheter tubes is about 0.45 ml min-1 cm-2. The higher perfusion rate resulted in a lesser platelet adhesion. At the highest perfusion rate tested, 0.92 ml min-1 cm-2, the number of adhered platelets decreased by 98% in the in vivo experiment. From the results of ex vivo and in vivo canine experiments, the saline perfusion catheters can be used as a very useful clinical armamentarium to prevent platelet and blood cell adhesion without using anticoagulants.