Abstract: A catheter introducer comprises an elongated sheath having a bore to receive a percutaneous needle therethrough. The proximal end of the sheath is secured to a head element having angularly spaced wing portions and defining two opposed parallel planar surfaces. The percutaneous needle has a transversely disposed U-shaped element secured to its proximal end which is snugly engagable with the planer sidewalls of the head portion and is secured thereto through a rib and slot interengagement of the arms with the planar surfaces. The sheath and the entire head portion are provided with diametrically opposed scorelines to permit the ready separation of the introducer through the application of a separating force to the wing portions. Such separation cannot, however, occur so long as the needle is fully inserted within the introducer due to the restraining action of the arms of the U-shaped element.