A mechanical steering lock for vehicles; the steering lock comprising: - a fixed attachment frame, - a lock which can be manually actuated by a mechanical key, - an elongated locking member, which is designed to angularly lock a steering shaft and is coupled to said fixed attachment frame in sliding manner in a rectilinear direction, - first actuating means operated by said lock to slidingly move the locking member between an angular locking position, in which the steering shaft is angularly locked with respect to the fixed attachment frame, and a releasing position, in which the free rotation of the steering shaft with respect to the fixed attachment frame is allowed, and - releasable retaining means for withholding said locking member in said releasing position, said releasable retaining means comprising: a) a retaining member, which is mobile with respect to said fixed attachment frame, and b) a mechanical transmission connected to said first actuating means for moving said retaining member away from and towards a retaining position, said locking member having an axial shoulder essentially orthogonal to said rectilinear direction; said retaining member comprising an abutting portion adapted to cooperate directly with said shoulder to stop said locking member; said mechanical transmission comprising: - a gear transmission comprising two toothed wheels (34,38), meshing with each other and rotational about respective axes, which are orthogonal to each other, and - a cam transmission arranged in series with said gear transmission and comprising a rotating cam and a tappet element cooperating with said rotating cam; characterized in that: • one of said two toothed wheels carries said rotating cam, and • said retaining member integrally carries said tappet element. - a fixed attachment frame, - a lock which can be manually actuated by a mechanical key, - an elongated locking member, which is designed to angularly lock a steering shaft and is coupled to said fixed attachment frame in sliding manner in a rectilinear direction, - first actuating means operated by said lock to slidingly move the locking member between an angular locking position, in which the steering shaft is angularly locked with respect to the fixed attachment frame, and a releasing position, in which the free rotation of the steering shaft with respect to the fixed attachment frame is allowed, and - releasable retaining means for withholding said locking member in said releasing position, said releasable retaining means comprising: a) a retaining member, which is mobile with respect to said fixed attachment frame, and b) a mechanical transmission connected to said first actuating means for moving said retaining member away from and towards a retaining position, a) a retaining member, which is mobile with respect to said fixed attachment frame, and b) a mechanical transmission connected to said first actuating means for moving said retaining member away from and towards a retaining position, - a gear transmission comprising two toothed wheels (34,38), meshing with each other and rotational about respective axes, which are orthogonal to each other, and - a cam transmission arranged in series with said gear transmission and comprising a rotating cam and a tappet element cooperating with said rotating cam; • one of said two toothed wheels carries said rotating cam, and • said retaining member integrally carries said tappet element.