A surgical safety scalpel having a handle, a blade fixed at one end of the handle, and a sheath slidably and inseparably attached to the handle. The sheath slides lengthways along the handle alternating between a blocking position in which the sheath covers the blade, and a ready position in which the blade is exposed and the sheath forms part of the grip. An aperture in the sheath and two stoppers on the handle form an interlocking mechanism for maintaining the sheath in the blocking position, and a third stopper on the handle prevents the sheath from sliding off the handle in the ready position.
