A strong movement of opposition to GMOs developed in the late 1990s in many countries, especially in Europe, although these technologies were presented from the outset as highly promising and their advantages were often highlighted. How can this rejection be explained? The aim of this paper is to answer that question through the case of France, which is fairly representative in this respect of various European countries, even if the opposition movement is here particularly strong. One examines various factors, actors and processes that have led to such strong opposition to GMOs that at this stage their development in Europe has almost totally been halted. In the first part of the article we recall the results of several recent surveys, showing the level of acceptance or refusal of genetic engineering in several countries. We then examine important factors of rejection: the focus on potential risks of GMOs and the extensive publicity given to them, coupled with the inadequacy of answers to these diverse criticisms, and a drawing up of an unfavorable risk-benefit balance. Lastly, we point out that various fears and objections to the evolution of agriculture and to the functioning of society (i.e. limited trust in institutions and firms) appear to be crystallized around GMOs.A strong movement of opposition to the agricultural applications of genetic engineering has developed throughout the world, particularly in some countries such as in the European Union. It has led to a moratorium in the EU -no transgenic crops are cultivated in the EU since 1999, except some Bt corn in Spain -and to hostility towards the importation of GM products, as well as to acts of open opposition. How can this strong hostility be explained when biotechnology, including genetic engineering, has generally been presented from the outset in a highly positive light and are still considered by many to be highly promising? The aim of this article is to present various factors and processes in the emergence and explanation of this opposition in France, a country in which it is particularly strong. We look at the French case which is fairly representative in this respect of various European countries; even if differences exist, depending on cultural characteristics and economic situations, a number of factors of opposition are found throughout.A great number of papers have already been published on opinions and attitudes toward GMOs in the EU. Because of this extensive literature, a global review is not presented here. These papers on the public perception of GMOs deal mainly with typologies or segmentations of consumer attitudes and with more static analyses of public perception of biotechnology as well as with agenda-setting, decisionmaking and regulation of this issue. Our approach is a little different and tackles more the factors of development and strengthening of GMO opposition in the general public. Such analysis seems especially important in view of the current deadlock. It seems useful to get a better understanding of this opposition mov...