An anti-skid system for vehicle wheels includes gripping elements which are intended to make contact with the tread of the wheel and are arranged at the free ends of arms joined to a central connecting body, a clamping element (15) apt to be fastened to the rim of the wheel, and a constraining assembly able to establish a connection between the arms (21, 22) and the clamping element (15), the arms (21, 22) being in the form of flexible laminar strips and the constraining assembly including at least one linear traction member (30) which is non-extendable, but adjustable lengthwise; an advantageous clamping element (15) which makes the system more cost-effective and mounting thereof on the wheel more convenient is also described.