A bioeconomical model was developed to study sustained management of the species Araucaria araucana (Mol.) Koch. The model characterizes its dynamics using transition matrices, which determine the evolution of each diameter class in time. The economic problem was modeled as the maximization of the Land Expected Value (LEV), which allows determining an optimal harvest structure and an optimal length of the cutting cycle under a sustained yield condition. An optimal sustained management was obtained for a cutting cycle of 340 years, with a LEV of 105.791 US$*Ha-1. Based on this optimal cutting plan, a cost of 35.626 US$*Ha-1 was estimated to impose sustained yields in these forests. The opportunity cost of applying the technical constraints effective at the moment for natural forest under selection harvest to Araucaria stands management was also estimated. This cost was calculated taking as base the optimal sustained management, reaching 64.340 US$*Ha-1. A remarkable policy implication is the existence of a significant incentive against sustainable management of this species. On the other hand, there is evidence of a high opportunity cost to the potential application of the actual management normative in these forests. Therefore, this cost should be contrasted with the potential environmental and social benefits that the implementation of this normative could generate. This evidence contributes to design policies which improve social welfare, but also that consider the true opportunity cost that face the owners of this resource.