Abstract: A folding knife featuring a locking sleeve at the junction between the blade and handle, so that the knife blade may be locked in both the open and closed positions. The locking sleeve has an enlargement which accommodates the end of the blade adjacent the tang, so that the locking sleeve may be partially rotated when the knife is closed and at least the sharp edge portion of the blade is within a recess in the handle, whereby the blade is restrained from egress from the handle. Suitable structure is provided to prevent axial sliding movement of the locking sleeve off of the end of the handle.