Abstract: A closed system canulating device for arterial and venous catherization, which includes a reservoir attached to the hub of a needle assembly and provided with an internal wire guide and valve to facilitate canulating an artery or vein with the needle and containing blood flashback in the reservoir during the canulation procedure. After canulation of the artery or vein is accomplished, a catheter guide wire is inserted through the valve and the wire guide located in the reservoir, into the needle hub and needle and finally into the artery or vein, to facilitate completion of the catherization procedure.