Private interest groups representing the interests of the largest multinationals try to impose themselves in Brussels in order to make European legislation evolve in their direction. Colossal sums are spent every year to carry out this work of influence. Thus, it is essential to question the weight that these interest groups represent in the elaboration of European laws. This study on the different lobbying strategies deployed by the multinational Monsanto allows us to highlight the degree of influence of the largest firms, the imbalances of representation at the European level and to understand the reasons for this.