When endoscopes are reprocessed correctly, endoscopy is a safe procedure. Recent incidents of insufficient reprocessing, however, have resulted in public concern. Results of a usability test of the reprocessing procedure identified that none of 24 users, naïve to the procedure, could reprocess endoscopes correctly, nor could they correctly complete any of the component tasks in the procedure. Five of the 76 subtasks were identified as particularly critical. These were 1) brushing the instrument channel, 2) attaching the channel plug and injection tube, 3) identifying leaks, 4) blowing water out of the endoscope's internal channels during high‐level disinfection, and 5) aspirating solution through the endoscope to remove debris loosened by brushing. Additionally, three themes were identified as causes of the majority of problems: 1) lack of visibility, 2) high memory demands, and 3) insufficient user feedback. Design recommendations for these problems are discussed. © 2012 Wiley Periodicals, Inc.