A revetment block for use in a revetment system, the block having top and bottom surfaces and pairs of opposed and substantially parallel side surfaces. One of the side surfaces in each of the opposed pairs has first and second projections and the other of the side surfaces in each of the opposed pairs has first and second recesses. The projections and recesses are sized and configured so that they mate with projections and recesses on the side surfaces of adjacent blocks. The bottom surface of the block may be provided with projections to enhance the frictional stability of the blocks. The blocks are connected together by cables which pass through tunnels between the side surfaces of the blocks. A sleeve fitted into each opening of the tunnel in the side surface is provided to protect the cables from breakage.