The specific aim of Phase I of the project is to perform preliminary tests of a new metal needle designed for use a venous needle (VN) with two- needle hemodialysis (U.S. Patient #5,662,619) in a setting simulating hemodialysis (inside a prototype of a vascular access, using flow rates of the VN and of the vascular access similar to the one found during dialysis). The studies will include: (A) Fluid mechanic experiments to demonstrated the effectiveness of the new VN. This will include: (a) experiments to measure of velocity, turbulence (Tu), wall shear stress (WSS) and positive pressure of the post VN flow, (b) flow visualization experiments (flow pattern, qualitative determination of Tu, recirculation). These measurements will be compared with the currently used VN. (B) Experiments to demonstrated the safety of the new VN: magnitude of hemolysis caused by new VN in comparison with the currently used VN. (B) Experiments to demonstrate the safety of the new VN: magnitude of hemolysis caused by new CN in comparison with the current used VN. (C) If the experiments demonstrated that the new VN decreases the velocity, Tu, WSS and pressure of the post VN flow, and causes equal or less hemolysis than the currently used VN, a phase II of the project will be conducted that will include additional fluid mechanic and in vitro, animal and human experiments. Access complications (intimal hyperplasia, stenoses, thrombosis and recirculation of dialysis blood) are the major cause of morbidity of the dialysis patients and the care of the access consumes > $1.5 billion/year. Hemodynamic factors are believed to play a leading role in initiating and maintaining endothelial damage and intimal hyperplasia. These cause "late"stenoses and this is a major cause of low access flow, recirculation of blood and thrombosis. The new needle is expected improve the hemodynamics of the vascular access and to decrease the occurrence and severity of complications, to improve the efficiency of dialysis and to prolong the access life-span, in particular PTFE, grafts and during dialysis with high blood flow rate (> 300-600 ml/min). PROPOSED COMMERCIAL APPLICATIONS: The new VN should replace the currently used VN and could be used by most of the patients receiving two-needle hemodialysis.