A guide system for use with an endoscope, and a method of use is
disclosed. The guide system can include a track, in the form of a rail,
and a mating member for engaging the rail. The guide system can also
include an accessory, such as an accessory guide tube through which a
medical instrument can be carried external of the endoscope. An end cap
can be provided to support the track relative to the distal end of the
endoscope.