In 1985, the Man-Systems Division at the Johnson Space Center initiated a program for the development of a whole body shower suitable for operation in a microgravity environment. Supporting this development effort has been a systematic research program focused on four critical aspects of the design (i.e., human factors engineering, biomedical, mechanical, and electrical) and on the interfaces between the whole body shower system and the other systems to be aboard the Space Station (e.g., the water reclamation and air revitalization systems).A series of tests has been conducted to help define the design requirements for the whole body shower. Crew interface research has identified major design parameters related to enclosure configurations, consumable quantities, operation timelines, displays and controls, and shower and cleanup protocols. Mechanical research has provided data on relative humidity, air and water temperatures and flow rates, liquid and gas separation, and system efficiency. Electrical research has characterized and quantified the power requirements for an optimized system. Biomedical research not only has provided data relevant to the identification and control of microorganisms introduced into the system by human usage but also has led to a new area of research; that is, a study of the effects of biofilm within the shower system.Defining the interfaces between the whole body shower system and the other Space Station systems and determining the impact of the whole body shower system on the performance of those systems are of paramount importance in this development program. In order to define these interfaces, a closed-loop test was conducted with the water reclamation system to evaluate the effects of the shower waste water on the design of the water reclamation system. Results from these tests are presented in a separate paper (1)*.