The validity of routine disinfection of gastrointestinal fibroscopes is reported. The Authors present their work based on 204 tests performed on gastroscopes and colonoscopes after manual disinfection performed by skilled nurses. All the instruments were kept in a 1:16 solution of glutaraldehyde-phenate for 10 minutes. Microbiological tests were performed half on sterile solution flushed on the outer part of the endoscope and half into the bioptic channel. Different groups of tests are reported. When strict asepsis was observed in handling the endoscopes all tests demonstrated to be sterile. When the endoscopes were handled as in usual routine, i.e. without sterile gloves and so on, 20% of the tests showed the presence of bacteria: these were only of types present in the environment. No real pathogens or antibiotic resistant strains were observed. The total disinfection procedure showed to be easy and quick to perform. No allergic or toxic reactions were observed. The importance of this procedure as a routine one in all endoscopy units is stressed considering also that literature data demonstrate the efficacy of glutaraldehyde-phenate against hepatitis and AIDS viruses.