This invention relates to an accessory for attaching to a needle to prevent needle stick injuries. The safety needle accessory is suitable for use with a hollow needle and comprises a needle hub surrounding the needle and a slidable sleeve slidably mounted on the needle hub. The slidable sleeve bears resiliently on the needle hub such that, in use, as the slidable sleeve is caused to move into a retracted position. A restoring force is generated within the slidable sleeve and on removal of the needle from the patient the restoring force causes the slidable sleeve to move into an extended position covering the needle tip. The safety needle locks in this position after removal of the needle from the patient.