A bone resection device for use in resection of bone during joint replacement surgery comprises a cutting tool housing (4), and at least one cutting tool (6, 8) which is fastened to the housing so that it can be moved reversibly between a retracted position and an extended position, in which it extends further from the housing in the extended position than in the retracted position. The cutting tool housing is attached to an elongate shaft (2) at or towards one end, the shaft having a control region at its other end from which the resection device is controlled while the cutting tool housing is located in the vicinity of bone tissue which is to be resected. The resection device includes a device (12) for controlling the position of the cutting tool relative to the housing, the device extending along the shaft and being movable relative to the shaft along the axis defined by the shaft, and being rotatable relative to the shaft around the said axis, the device engaging the cutting tool by means of a cam arrangement in which one of the control device and the cutting tool has an elongate cam track (34) formed in it and the other has a reciprocating follower (18) which can slide in the track, the track being non-parallel to the axis of the shaft. Movement of the control device along the shaft causes relative movement of the follower along the cam track, to cause the position of the cutting tool relative to the housing to change.