A suction control unit placed on an endoscope to control application of suction through at least one of two working channels of the endoscope. The suction unit has first and second valves with first and second valve openings, at a proximal end, that lead through to a distal end, which is adapted to be placed on the first and second ports of the two working channels. The suction unit has a channel extending between the first and second valves, an opening extending from a front wall to a rear wall of the housing and through the channel, and a switcher having a handle and a shaft with a through hole. When the shaft is placed within the opening and in a first position, suction is applied to both the working channels. When the shaft is placed within the opening and in a second position, suction is applied to only one of the two working channels.
