The Pauldrach Endocleaner was evaluated for the disinfection of gastrointestinal fibrescopes, and found to be a convenient, relatively inexpensive machine for use in endoscopy clinics. An experimental procedure was designed, for use with the endocleaner, which allowed application of an inoculum of Pseudomonas aeruginosa to a Fujinon OX52 endoscope and its subsequent quantitation before and after disinfection procedures. Using aldehyde based disinfectants ('Cidex', 'Kohrsolin' and 'Gigasept') it was possible to achieve a 99.999% reduction in the recovery of viable Ps. aeruginosa with a minimum exposure time of 20 min 'Dettox ABC' and buffered hypochlorite (100 ppm) were less effective achieving an approximately 99% reduction with a minimum exposure time of 30 min. Following apparently adequate disinfection and irrespective of the disinfectant used, the endoscope was found to be heavily contaminated with Ps. aeruginosa when examined after overnight storage at room temperature thus emphasising the need for meticulous disinfection of instruments prior to use in a day's list.