Recent progress in colonof iberscope has made the possible understanding of the direct observation on the entire colon by the application of Sliding Tube Method. In some cases, however, it is difficult to introduce the scope into the right sided colon because of the alongation and the adhesive condition of a sigmoid segment. We devised an over coat-tube equipped with a channel apparatus for pressing down the marked loop formation and for turning counterclockwise to achieve an alpha(a) conf igration in the sigmoid segment. A "leading tube" we named is an elastic tube of which diameter is 1.8 (inside) and 2.2 cm (outside) and which is 88 cm in length. This tube is changeable into three formes, that is flexible, straight, and S-shaped. We have applied the "leading tube" to 12 cases and obtained some satisfactory results. This paper shows the frame and the method of this tube and the mesults which we experienced.