An apparatus for percutaneously implanting a localization wire into a tissue mass comprises a cannula with a preloaded localization wire. An actuator is provided to effect the relative movement of the cannula and localization wire such that a distal end of the localization wire is exposed to the tissue mass. A method for implanting a localization wire includes inserting a cannula with a preloaded localization wire into a tissue mass and relatively moving the cannula and localization wire to expose a portion of the localization wire to the tissue mass.