A major limitation for organic producers in the UK is the lack of information on the relative performance of modern crop varieties grown under organic farm conditions. To address this, a number of organic cereal variety trials were established on organic farms in the south and east of England. The aim is to determine the relative performance of leading cereal varieties grown under organic conditions and to provide background information for potential breeding programmes. Additionally, it is well established that mixtures of cereal varieties grown in the field can have positive benefits over pure stands in terms of disease and pest restriction and buffering against variation in environmental conditions. Therefore, mixtures of selected varieties have been included within the trials to quantify this benefit.