This document gives general requirements and guidance intended for three main uses: % implementation of ISO/TC 34/SC 9 or ISO/TC 34/SC 5 standards for detection or enumeration of microorganisms, named hereafter specific standards ; % good laboratory practices for food microbiology laboratories; % guidance for food microbiological laboratories on the technical requirements for accreditation to ISO/IEC 17025. The requirements of this document supersede corresponding ones in existing specific standards. Additional instructions for molecular biology examinations are specified in ISO 22174. This document covers examination for bacteria, yeasts and moulds and can be used, if supplemented with specific guidance, for parasites and viruses. It is not applicable to examinations for toxins or other metabolites (e.g. amines) from microorganisms. This document applies to microbiology of the food chain, including food, animal feed, the food production environment and primary production environment. This document is also applicable to the microbiological examination of water where water is used in food production or is regarded as a food in national legislation. The purpose of this document is to help to ensure the validity of food microbiology examinations. In particular to ensure that general techniques for conducting examinations are the same in all laboratories, to achieve consistent results in different laboratories, and to contribute to safety of laboratory personnel by preventing risks of infection.