Objective: To assess whether monitoring every loads of automated washer-disinfectors (AWDs) by testing the last rinse water with Adenosine Triphosphate (ATP) would have an added value to document effective and reproducible AWD processes. Methods:Every load monitoring (ELM) of the last rinse water with ATP was performed on three AWDs at the sterilization department of a 329 acute-bed hospital in Italy. No change were made in the routine procedures, except the last rinse water of a process was collected with a water sampler and tested on ATP. Data from negative controls and empty cycles were also obtained for comparison. ATP values were analysed according to AWD, load, and process characteristics. Conclusion:The measurement of ATP in the last rinse water of AWDs showed that characteristics and quantities of the load relate to the ATP readings. The test is advised as an informative additional test to visual inspection for monitoring every load of an AWD.