Hygienic Performance of Commercial Dishwashers with Water-Change System -A nE x p er i m en t a lS t u d y Commercial dishwashers are used in community facilities such as hospitals, refectories, nursing homes or food services. In this area, kitchen and food hygiene is of great importance to ensure consumer health. The aim of this study was to verify the hygienic performance of commercial dishwashers with a water-change system by use of bioindicators. This test method is described in DIN SPEC 10534. Micrococcus luteus was used as the test germ instead of Enterococcus faecium as it imposes no pathogenic risk. Micrococcus luteus was identified in initial studies as an appropriate test germ for hygiene studies. Cleaning and rinsing temperatures and holding time of the cleaning program were varied. High rinsing temperature with a constant cleaning temperature and high cleaning temperatures with a constant rinsing temperature led to a reduction of the viable cell count. Increasing the cleaning temperature resulted in a higher decrease of the viable cell count than increasing the rinsing temperature.