A safety IV catheter assembly comprising: a needle, a tubular catheter, a catheter hub attached to the proximal end of the tubular catheter, a needle hub attached to the proximal end of the needle, the needle comprising a needle tip and a needle shaft which is inside the tubular catheter when in a ready position, the needle being moveable from the ready position in which the needle tip is outside the catheter hub to a retracted blocking position in which the needle tip is within the interior of the catheter hub, and a spring clip needle guard which is releasably connected to the inside of the catheter hub in the ready position and which covers and blocks the needle tip in the retracted blocking position, the spring clip needle guard comprising a rear wall (106, 168) with upper and lower ends which both contact the inner wall of the catheter hub in the ready position, whereby the rear wall (106, 168) includes an opening (58, 170) through which the needle shaft passes and an arm (98, 50) which extends distally of the rear wall (106, 168) and whose distal end extends to a distal arm (112, 152) which in turn terminates in a curved lip (114, 154), whereby the needle shaft passes through the spring clip needle guard and applies an outward radial force on the arm (98,150) by means of engagement with lip (114, 154) so as to urge the distal end of the arm (98, 150) into engagement with the inner wall of the catheter hub in the ready position to securely maintain the spring clip needle guard within the catheter hub, whereby the distal arm (112, 52) covers and blocks the needle tip in the retracted blocking position, and whereby in the retracted blocking position the spring clip is retained on the needle and will be removed from the catheter hub when the needle is completely removed. a needle, a tubular catheter, a catheter hub attached to the proximal end of the tubular catheter, a needle hub attached to the proximal end of the needle, the needle comprising a needle tip and a needle shaft which is inside the tubular catheter when in a ready position, the needle being moveable from the ready position in which the needle tip is outside the catheter hub to a retracted blocking position in which the needle tip is within the interior of the catheter hub, and a spring clip needle guard which is releasably connected to the inside of the catheter hub in the ready position and which covers and blocks the needle tip in the retracted blocking position, the spring clip needle guard comprising a rear wall (106, 168) with upper and lower ends which both contact the inner wall of the catheter hub in the ready position, whereby the rear wall (106, 168) includes an opening (58, 170) through which the needle shaft passes and an arm (98, 50) which extends distally of the rear wall (106, 168) and whose distal end extends to a distal arm (112, 152) which in turn terminates in a curved lip (114, 154), whereby the needle shaft passes through the spring clip needle guard and applies an outward radial force on the arm (98,150) by means of engagement with lip (114, 154) so as to urge the distal end of the arm (98, 150) into engagement with the inner wall of the catheter hub in the ready position to securely maintain the spring clip needle guard within the catheter hub, whereby the distal arm (112, 52) covers and blocks the needle tip in the retracted blocking position, and whereby in the retracted blocking position the spring clip is retained on the needle and will be removed from the catheter hub when the needle is completely removed.