Cleaning is the single-most-important step in making a medical device safe for handling. It is also extremely important as a preparatory step before any subsequent disinfection or sterilization process. This article addresses the rationale for cleaning of medical equipment or devices before any further processing and includes examples of infectious complications associated with inadequate cleaning. In addition, discussion is presented concerning the relationship between cleaning and any subsequent processing before patient use. Guidance relative to the use of various cleaning agents is also provided. Additional emphasis on the necessity of following manufacturer's recommendations on cleaning agents and procedures is noted.