Abstract: Single needle vascular access systems, devices and methods for use in hemodialysis and apheresis procedures. A single needle vascular access device includes a body having an upper and lower passage with both in fluid communication with a vascular dilator. A cannulation needle is guided through the lower passage and vascular dilator to cannulate a graft or fistula. Following cannulation, the dilator is gently introduced into the vessel. The cannulation needle is removed, and a venous tube is introduced through the upper passageway through the vascular dilator and into the fistula or graft. Blood is then removed from the body through the vascular dilator side orifices and returned through the venous line. Depending on the clinical situation, the vascular dilator can be used with one or both needles of a conventional two needle system. In the later case, the vascular dilator may be connected to the dialysis tubes using conventional standard connectors.