Over the last two decades, the Department of Health commissioned three National Research Teams (Southampton, London and Edinbu rgh) with a brief to investigate if protein residuals is a concern on reprocessed re-usable surgical instruments through a washer disinfector. All three research teams developed a system to measure residual proteins on surgical instruments and all came to the same conclusion, that protein residuals were indeed present on pro cessed instruments, in particular prion protein which has been proven to be extremely difficult to remove with current wash processes and chemistries. On completion of the research, the Advisory Committee on Dangerous Pathogens (ACDP) Guidance was updated, which in turn pre-empted the update to HTM / WHTM 01-01. The updates recommended additional measures to combat residual proteins on surgical instruments. These were alternative detection systems for monitoring protein residuals on instruments (in-situ protein detection), reducing the time from patient to washer disinfector for high risk instruments, if there is a delay in reprocessing (preferably with the 6 hour time frame) systems mu st be place to keep instruments moist and finally protein based fully quantifiable process challenge devices should be considered as they come to market.