Abstract: A system for permitting substantially bloodless percutaneous entry into an artery or vein of a patient. The system comprises a needle assembly, a needle hub attachment assembly having a hemostatic segment, and a wire guide inserter (curve straightener) or a wire guide holder also having a hemostatic segment. The components are assembled in a leak-free arrangement, and a fluid passageway for withdrawing blood is established through the system. Each of the hemostatic segments opens to permit passage of a wire guide therethrough, but re-seals to prevent flow of blood therethrough. The needle hub attachment assembly preferably includes a fluid-receiving chamber to permit the clinician to see the first squirt of blood as it enters the system.