Bacterial contamination of gastrointestinal fibre-endoscopes is a potential source of clinically significant infection. Aqueous 2% alkaline glutaraldehyde adequately disinfects fibre-endoscopes but may cause serious sensitivity reactions among endoscopy staff. A new 'closed-system' disinfecting apparatus is described that disinfects with glutaraldehyde for 30 minutes before an endoscopy session, for two minutes between patient procedures, and for 10 minutes before storage. Bacteriological cultures of the endoscope after disinfection were virtually sterile. Extremely low glutaraldehyde vapour levels were detected by gas chromatography in endoscopy room air during disinfection procedures. This relatively simple apparatus offers rapid, effective, and safe disinfection of fibre-endoscopes.