A surgical instrument (4), a handle (2) for use with the surgical instrument and a surgical instrument system are described. The surgical instrument and handle comprise complementary features to ensure a secure connection between the instrument and handle. hi one embodiment the instrument comprises an outer shaft (12), an inner shaft (14) and an operative portion. The outer shaft comprises opposed flat surfaces (16) allowing it to be engaged by the handle on the fiat surfaces. The inner shaft comprises a latch surface (26) at its proximal end for engaging a latch mechanism in the handle. In other embodiments a radial bore (18) is provided in the outer shaft of the instrument. This can be engaged by an elongated member in the handle.
