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.