This paper is a critical review of the issues related testing and registering of microbiocides meant for use on environmental surfaces and medical devices. It highlights better ways to test microbiocides and to attain global harmonization of testing and product registration. It also details the known and potential dangers of microbiocide use and what to consider in choosing such formulations for optimal safety and effectiveness. Journal of Applied Microbiology 2006 ; 101 743-753.