This article based on the methodology of the investigation-action-participation, has the purpose in synthesis tight to reflect and question us about the role and place of the unions in the socialist construction. In the socialist transition, organized workers would be the protagonists of the economic, organizational, management and decision-making processes. The subject is complex, multidimensional, often rejected and misunderstood, however it has been very controversial, occupying an extraordinary place in the conceptions of the founding classical Marxism, later developed by Vladimir Ilyich Lenin, Rosa Luxemburg, Antonio Gramsci, among others.