Disinfection validation is a FDA Good Manufacturing Practices (GMP) requirement. Quality assurance departments are required to determine the effectiveness of given disinfectants using standard test strains under controlled conditions, per the protocol published by the Association of Official Analytical Chemists (AOAC). This protocol is used by manufacturing for in-house disinfection validation. Disinfectant selection can be based upon microbial populations found at the facility. High, intermediate, and low level disinfectants are used in most aseptic processing areas. Validation of the selected disinfectant is based upon repetitive testing under laboratory conditions with concomitant microorganisms. Test conditions for validation processes are based upon the standard AOAC Hard Surface Carrier Method. The procedure is a qualitative carrier test, using glass carriers and standardized bacterial cultures. This paper will concentrate on the selection and validation of disinfectants for biotechnology clean rooms and equipment. The emphasis here will be on developing a standardized testing program that will meet the intent of the FDA GMP's. The main objective of this paper is to instruct the reader on validating disinfectants used in clean room areas. Disinfectants must be challenged under actual shelf life and use conditions. Suitable microbiological challenge methods will be discussed along with appropriate validation protocols. Quality control methods for in-process disinfectant testing will emphasize original data from appropriate indicator organisms and inactivators.