A flat coaxial cable assembly comprising a plurality of parallel coaxial cables disposed in coplanar configuration, each cable being self-contained and with a center conductor, dielectric material around the conductor and a shield of conductive material around the dielectric material, a plurality of drain wires disposed between alternate pairs of adjacent coaxial cables, the drain wires having conductive contact with the shields of the pair of adjacent cables, and a sheath of insulating material encasing the cables and the drain wires with portions thereof on opposite sides of the cables bonded together by way of the spaces between the cables where the drain wires are omitted and at the sides of the outermost cables.