A sheath (1) for protecting an endoscope probe projecting from an endoscope head. The sheath (1) comprises: an elongate tube (1) with a bore for receiving the endoscope probe a clamp (5) at or near a proximal end of the sheath for gripping the endoscope head or the endoscope probe and a window (3) which is bonded to a distal end of the elongate tube. The window (3) is formed from an elastomeric material. An endoscope probe is inserted into the bore of the elongate tube (1) so that it engages the window (3) , and a force is applied so that the window is pressed and stretched against the elongate tube. The application of force causing a wall thickness of at least part of the window to decrease. The clamp (5) comprises a resilient member (4) with an elongate opening which can be opened to admit the endoscope probe by compressing the resilient member (4) in line with the length of the elongate opening.