This International Standard specifies how to use the standards for sampling strategies (EN/TS 21568), nucleic acid extraction (ISO 21571), qualitative nucleic acid analysis (ISO 21569), quantitative nucleic acid analysis (ISO 21570) and protein-based methods (ISO 21572), and explains their relationship in the analysis of genetically modified organisms in foodstuffs. It contains general definitions, requirements and guidelines for laboratory set-up, method validation requirements, description of methods and test reports. It has been established for food matrices, but could also be applied to other matrices (e.g. seeds, feed and plant samples from the environment).