A disposable endoscope sheath having a flexible tubular member joined to a grasping member, the tubular member having a closed distal end, and an annular, elastic locking ring temporarily mounted onto the distal end of the grasping member, whereby the locking ring is rolled onto the tubular member after the sheath has been disposed onto an endoscope shaft, the size and elasticity of the locking ring being chosen such that the tubular member is securely affixed to the endoscope shaft.