The large Brazilian retail companies are undergoing strong geographical expansion in order to enhance shareholders value by gains of scale and greater negotiation power with suppliers. The entrance into a new geographical market, however, presents many uncertainties that can affect the return of these new stores. The traditional approach of discounted cash flow method, does not take into account that the opening of the first new store reveals new market information that allows the investor to optimize his penetration strategy in this market. This dissertation proposes the use of the Real Options Theory to value the project to expand a retail company to a new market, by valuing the managerial flexibility of expansion and abandonment available to the company. By incorporating the value of the operation of a second store in case of the exercise of the expansion option , the proposed model increases the total value of the project when compared to the net present value calculated by the discounted cash flow analysis. The Real Options Theory was superior in the project valuation as the value of the project calculated by the discounted cash flow analysis is underestimated by not considering the existing flexibility in the project.