In the last four decades there is a renewed interest within the economic theory for the institutional structures. Numerous, multiple and often unpredictable effects of institutions on economic process are differently reflected among the leading schools of economic analysis. Certainly, in this sense, the greatest attention should be given to the stream of economic thought known as institutional economics. This heterogeneous research orientation today is already clearly differentiated on Veblenian and the new institutional economics. The paper will make, in the light of its recorded achievements and the subjects of interest of its main protagonists, a general insight into the new institutional economics.