The use of disinfectants as agents to control microbiological contamination of an environment is well established and is governed by regulatory bodies in both Europe and the United States. Data demonstrating the efficacy claim of a disinfectant, whether it is bactericidal, fungicidal, sporicidal or viricidal, is a clear requirement of BPR or EPA for a disinfectant manufacturer to achieve registration. In Europe, European Norm (EN) standards provide reference to required test methods to be used by disinfectant manufacturers to support claims of microbiocidal activity. This presentation provides an overview of the EN standards available for disinfectant efficacy testing and whilst providing an oversight to specific test phases performed for registration, will also provide guidance on how these standards may be utilized for end user validation. The presentation will review factors to consider when establishing parameters and conditions that may be modified from the standard for the purpose of validation.