A biopsy device includes a hydraulic drive assembly, a drive mechanism, and a biopsy member. The hydraulic drive assembly includes a chamber housing that defines a proximal chamber, a distal chamber, and a transition chamber that collectively form a continuous passage in the chamber housing. The proximal chamber has a first transverse area and the distal chamber has a second transverse area, with the first transverse area being larger than the second transverse area. A drive piston is located in the proximal chamber and a driven piston is located in the distal chamber. A hydraulic fluid fills a cavity between the drive piston and the driven piston to establish a hydraulic connection between the drive piston and the driven piston. The drive mechanism is connected to the drive piston to move the drive piston in the proximal cylinder. The biopsy member is connected to the driven piston.
