This paper seeks to understand the development of the Austrian School market theory, as an alternative to the Neoclassical School (mainstream). For the elaboration of the paper is necessary to analyze the epistemological and methodological reasons and differences between the concepts of efficiency for the two schools. We conclude that Austrian School market theory is presented as a better alternative to the mainstream market theory, which presents illusive assumptions and concepts. Thus, we stir up the emergence of new perspectives that can contribute to the academy and to overcoming misconceptions that lead to erroneous conclusions.