Tubing in a borehole is removed using a rotary milling tool comprising a plurality of elements projecting from or extensible from the body of the tool. The elements are distributed azimuthally around the tool body. The elements comprise cutters to remove material from the tubing and outward facing guide surfaces for sliding contact with an inner surface of the tubing. As the tool is rotated and advanced, forward cutters contact the inner surface removing material from the tubing and exposing a renewed interior tubing surface with a diameter swept out by the cutter. The outward facing guide surfaces extend the same distance from the tool body as the forward cutters producing a sliding contact with the newly created inward facing surface. Further cutters, disposed behind the outward facing guide surfaces, with respect to motion of the tool through the tubing, remove the remaining portion of the tubing.