Adopting the transaction as unit of analysis, he is objective of the present study, to investigate the impact of the electronic commerce, while a transacional technology, in the inherent costs of transaction to the economic activities. For the comparison of different forms of exchange of information, the study it demonstrates with simulation of communities formed for purchasers and salesmen, who the properties of the electronic commerce make possible an increase of efficiency in the reputation mechanisms, allowing a reduction in the costs of contract imposition. On the basis of the conclusions of the experiments and in the literature of the subject, are raised possible implications of this impact in the structure of markets and industries.