Abstract: The invention provides a protective sheath for an intermittent I.V. therapy needle to protect medical personnel against accidental self puncture while performing intermittent I.V. therapy. The sheath is a flexible transparent plastic tube having an internal septum which provides two separate interior compartments. One compartment is adapted to house a needle and a portion of the needle hub, providing an enclosed sterile environment when the device is attached to the needle assemblage of a secondary medication source. The second compartment is adapted to be releasably affixed to the exterior of an eccess port at a Y-site located on intravenous tubing used for intermittent I.V. therapy. The walls of the sheath fold and compress as the needle is advanced through the internal septum into the Y-site where the contents of the secondary medication source are infused into the I.V. tube main line through the Y-site.