Abstract: A safety needle assembly comprises a cannula holding member, a cannula fixed to the cannula holding member, and a safety device mounted on the cannula holding member. The cannula holding member includes one or more outwardly directed fins extending longitudinally along at least a portion of the cannula holding member. The safety device includes a collar adapted to be mounted on the cannula holding member and a sheath. The sheath possesses an interior bounded by a back wall and a pair of oppositely positioned side walls, and also includes an opening positioned opposite the back wall. The sheath is also provided with at least one fin engaging member connected to the back wall and extending from the back wall in a direction toward the opening. The fin engaging member is spaced from the side walls of the sheath.