A surgical instrument having a handle, an elongate shaft protruding from the handle and an end-effector located at the end of the shaft is described. In order to allow for rotation of the end-effector the shaft is connected to a rotation wheel mounted on the handle, towards the rearward end of the handle proximal to the user. The rotation wheel is in the form of a thumbwheel, having an ergonomically designed shape that tapers from the distal direction to the proximal direction, with the angle of the taper matching the angle of the outer surface of the handle. The outer tapered surface of the thumbwheel has a number of shaped cut-out or scalloped portions arranged around the outer circumference of the wheel, and arranged in use to receive the tip of a user's thumb to allow the user to rotate the wheel in order to set the rotational orientation of the end-effector. Such an arrangement provides a comfortable and easy to use instrument. <；Figure 14b>；
