How are the four billion euros in subsidies allocated by the State to union structures spent each year? What are gifts of all kinds from local authorities for? This survey, which began in April 2011, paints a picture of a real trade union business that is thriving in France. It also reveals the existence of secret flows that irrigate the unions, between parallel systems of raising money, capturing subsidies, and very profitable satellite structures. An opacity that extends to works councils, strongholds of dubious financial flows and benefits of all kinds. This text is also a plea for a return of union structures to their raison d'être. After having investigated in France, in Germany, in Sweden, and in the United States, the authors note that there are lines of force which could be inspired by the French trade unions to renovate themselves.