Genetically modified organisms (GMOs) cannot be marketed within the European Union (EU) as food or food ingredients without following the requirements of the Novel Foods Regulation . In addition to safety evaluation, that regulation also sets the conditions for the labelling of GMO-containing food.Two GMO products (Roundup-Ready® soybean and Bt-176 maize) had been placed on the EU market before the Novel Foods Regulation came into force , . A specific Council Regulation has therefore been approved to deal with the particular labelling requirements for these GMOs . More recently, the so-called 'threshold regulation' specifies that foodstuffs must be subject to labelling where material, derived from these genetically modified organisms is present in food ingredients in a proportion above 1% of the food ingredients individually considered .The availability of validated methods for the detection and quantification of genetically modified organisms (GMOs) in food samples is therefore a key component for the implementation of the European Unions' Novel Foods Regulation.Qualitative methods can be used as an initial screening of food products to investigate whether GMO specific compounds (proteins and/or DNA) are present. Qualitative analysis could thus be performed on products, sampled from the shelves of supermarkets or from the supplies stored in harbour stockpiles. It is important to highlight the consequences of the two different components of the regulatory framework since they have affected the technical layout of this report. Compliance with the labelling requirements must be assessed in a two-step procedure. By screening products such as biscuits, it is feasible to know if the food has been made from a particular GMO. However, screening techniques are known to be extremely sensitive since they might detect 0.01% of GMOs, in other words it is sufficient to have 100 milligram of GMO soybean per kilogram of soybean to score a positive result. Such a low amount is far below the 1% limit that is set as a threshold level for labelling. Furthermore, that limit is set at the level of ingredients and therefore, if a final product scores positive after a screening method, its respective ingredients should be assayed quantitatively to assess if it contains less or more than 1% GMO. In the latter case, the final product should be labelled.   If the qualitative analysis provides an indication for the presence of an authorised GMO, a subsequent quantitative test should give a decisive answer concerning the labelling requirement. Labelling is required if it can be demonstrated, at the food ingredient level, that there is more than 1% of the GMO present. It can therefore be summarised that a qualitative method for GMO detection should be suitable for ingredients as well as for complex food matrices, whereas a quantitative method should perform well on raw materials and on food ingredients.The current study focuses on the detection of Roundup-Ready® soybean and Bt-176 maize because these were the first GMO products authorised in the EU for food use and subjected to specific labelling requirements.Outline of the projectThe aim of this project was to use Roundup-Ready® soybeans and Bt-176 maize in collaborative trial studies to validate:-a qualitative screening method for its suitability to detect GMOs in processed food-a quantitative method to estimate the concentration of GMOs in raw materials.Both methods are based on the amplification of DNA by the so-called polymerase chain reaction (PCR) and on the visualisation of the DNA fragments generated by using gel electrophoresis. Twenty-three European laboratories participated in the validation studies.