A needle shield assembly having a single-use cannula lock of the present invention includes a needle cannula having a proximal end, a distal end and a lumen therethrough. A hub includes a proximal end for connection to a fluid transfer device and a distal end connected to the proximal end of the needle cannula. A collar is rotationally connected to the hub so that the collar can be rotated around the hub. An elongate needle cover removably engages the hub and covers the needle cannula. An elongate needle shield having a proximal end and a distal end is hingedly connected, through its proximal end, to the collar. The needle shield includes two sidewalls defining a longitudinal opening and a back wall between said side walls defining a recess having an interior surface. The needle shield is capable of pivoting from an open position wherein the needle cannula is exposed, to a closed needle protecting position wherein at least part of the needle cannula is within the longitudinal opening of the needle shield. The needle shield assembly further includes structure for preventing the needle shield from pivoting into the closed position unless the needle cover is removed, and structure for locking the needle shield in the closed needle protecting position when the needle shield is pivoted into the closed position. The structure for locking traps the needle cannula in the longitudinal opening of the needle shield.