The present invention relates generally to guidewires with a high level of torquability, flexibility, and elasticity. In an embodiment, a guidewire comprises an elongate shaft having an outside diameter. The shaft may include a filler and a polymeric matrix, wherein the filler includes a plurality of wires, wherein the matrix substantially surrounds the filler, and wherein the outside diameter of the shaft is sized appropriately for being disposed within a lumen of an intravascular catheter.