A biopsy device (10, 10') comprising: • a housing; • an outer cannula defining an axis and including a tissue-receiving cavity, the outer cannula extending to a tip distal from the housing; • a cutter cannula; • a vacuum generating mechanism in air-flow communication with the cutter cannula and the tissue-receiving cavity, the vacuum generating mechanism including a vacuum chamber and a piston; • a first biasing device adapted to operate the vacuum generating mechanism to produce a vacuum in the tissue-receiving cavity; • a second biasing device adapted to advance the cutter cannula across the tissue-receiving cavity; • the outer cannula being in a fixed axial relationship with respect to the housing; • the cutter cannula being within the outer cannula and being movable along the axis relative to the outer cannula and the tissue-receiving cavity; • the vacuum chamber being concentric with the cutter cannula, and the piston being in the chamber in air-sealing relationship with the chamber and around at least a portion of the cutter cannula such that the piston and cutter cannula are enabled to move independent of the other while maintaining the seal; • the first biasing device being adapted to move the piston over the cutter cannula axially away from the tissue-receiving cavity to produce the vacuum in the tissue-receiving cavity; and • the second biasing device being adapted to advance the cutter cannula through the piston, whereby the first biasing device operates the vacuum generating mechanism to draw tissue into the tissue-receiving cavity before the second biasing device advances the cutter cannula to cut the tissue. • a housing; • an outer cannula defining an axis and including a tissue-receiving cavity, the outer cannula extending to a tip distal from the housing; • a cutter cannula; • a vacuum generating mechanism in air-flow communication with the cutter cannula and the tissue-receiving cavity, the vacuum generating mechanism including a vacuum chamber and a piston; • a first biasing device adapted to operate the vacuum generating mechanism to produce a vacuum in the tissue-receiving cavity; • a second biasing device adapted to advance the cutter cannula across the tissue-receiving cavity; • the outer cannula being in a fixed axial relationship with respect to the housing; • the cutter cannula being within the outer cannula and being movable along the axis relative to the outer cannula and the tissue-receiving cavity; • the vacuum chamber being concentric with the cutter cannula, and the piston being in the chamber in air-sealing relationship with the chamber and around at least a portion of the cutter cannula such that the piston and cutter cannula are enabled to move independent of the other while maintaining the seal; • the first biasing device being adapted to move the piston over the cutter cannula axially away from the tissue-receiving cavity to produce the vacuum in the tissue-receiving cavity; and • the second biasing device being adapted to advance the cutter cannula through the piston, whereby the first biasing device operates the vacuum generating mechanism to draw tissue into the tissue-receiving cavity before the second biasing device advances the cutter cannula to cut the tissue.