An endoscope for use with an elastomeric sheath for performing an endoscopic procedure. The endoscope includes a body, an insertion tube extending away from the body and terminating at a distal end portion, and a sheath retainer connected to the distal end portion of the insertion tube for releasably retaining the sheath on the insertion tube in a substantially fixed position during the endoscopic procedure. The sheath is an elastomeric member movable between a radially expanded position and a contracted position, and the sheath is biased toward the contracted position. The sheath retainer is a generally C-shaped member having a pair of retaining tabs spaced apart from each other and extending away from an outer surface of the insertion tube's distal end portion to define a working channel retaining area therebetween. The retaining tabs are positioned and sized to engage a portion of the sheath at its distal end portion and to prevent the distal end portion of the sheath from moving axially relative to the distal end portion of the insertion tube, particularly during an endoscopic procedure.