With the development of genetically modified organisms in agriculture, new concerns about crop management have been addressed. Apart from the evaluation carried out with the regulation process before marketing, observations under current agricultural practices are required in order to build suitable agronomic management and design a monitoring system. Many studies have been carried out in France since 1995 and preliminary results suggest that a more integrated crop management should be required. In the present paper, we will first analyse the impacts which may be associated with the possible cropping of genetically modified varieties of oil rapeseed tolerant to an herbicide. These impacts have been investigated with different complementary approaches. Given the current knowledge, we can draw some conclusions regarding agronomic management and biovigilance monitoring. These results show the essential close connection between evaluation, management and biovigilance and emphasize the fact that studies must be pursued at a larger scale.