The development of flexible fiberoptic bronchoscopy was an important technologic advance in the diagnosis and management of patients with pulmonary disease. However, reliable decontamination and sterilization of these delicate instruments have been difficult. Many physicians routinely use a solution of povidone-iodine diluted in 70% ethyl alcohol and water to decontaminate fiberbronchoscopes, despite the fact that these iodophor compounds were developed as skin antiseptics and not as germicidal disinfectants for decontaminating instruments. We isolated a strain of Mycobacterium tuberculosis on a surveillance culture from a bronchoscope after it had been cleaned and disinfected with an iodophor solution. In another hospital, we documented the transmission of M. tuberculosis from one patient to another by a bronchoscope that had been disinfected with a commonly recommended iodophor solution. We then studied the tuberculocidal efficacy of various iodophor preparations used with exposure times from 10 to 30 min. In several experiments these iodophors failed to kill M. tuberculosis. Because iodophors do not reliably kill M. tuberculosis, they should not be used to disinfect fiberoptic bronchoscopes.