The introduction of genetically modified (GM) crops has caused a fierce public debate in Europe.Much of the controversy centres on possible risks to the environment. A specific problem here is thatrisk perception of the scientific experts differs from that of the public. In this paper, risks associatedwith herbicide-resistant crops are presented from the point of view of experts and lay people. In thepublic perception, herbicide-resistant (HR) crops are troublesome because of their association with twotechnologies: genetic engineering of crops and the use of herbicides. These technologies are perceived asrisky because they seem to share certain features: in particular, their long-term effects are unknown andthey are dreaded. Other value questions also come into play. The public seems to be concerned that risksare not outweighed by usefulness, that using HR crops is the wrong path to sustainable agriculture, thatthe individual's right to choose GM-free products may be violated, and that these crops are unnatural. Incontrast, on the issue of the uncertainty inherent in risk assessment, experts and the public seem to sharea good deal of ground.