A highly flexible radiopaque cable includes two, and preferably three or more strands of nickel-titanium (NiTi) alloy wire which are twined about a higher density core wire preferably made of at least one of silver, gold or platinum-iridium to form a wire rope. The wire rope is drawn through successive dies to reduce its diameter until the outer surface of the cable is substantially smooth, the cross section of the cable is substantially circular, and the overall diameter of the wire rope is reduced by 20-50%. The cable is then annealed to remove the effects of cold working. The resulting cable has been found to have a substantially equal or improved flexibility (i.e., a lower modulus of elasticity) relative to single strand nickel-titanium wires of the same diameter and a higher radiopacity. In an alternative embodiment, no core wire is utilized, and the higher density wire is drawn with two or more strands of NiTi wire. In another embodiment, the higher density wire is radioactive.