Abstract: An improved catheter assembly is provided wherein a cannula depends from a catheter body having a first passageway therethrough communicating with the cannula through which an introducer needle may be introduced and removed. The assembly is provided with a second passageway communicating with the cannula through which a fluid may be introduced. A moveable means is provided disposed across the first passageway and moveable from a first position to a second position. The moveable means is provided with a duct passing therethrough, the duct being coaxial with the first passageway when the moveable means are in a first position to allow the introduction of removal of the introducer needle. Thereafter, the moveable means are adapted to be moved into a second position in which the access of the duct is displaced to be non-coaxial with the first passageway, and hence out of communication therewith and with the moveable means in the catheter body cooperating to seal the duct from the first and second passageways.