Our purpose with this work is to present and discuss an application of the System Dynamics method in a Brazilian agricultural company, discussing the challenges, benefits, problems and results of a consultancy project aimed to support the company’s strategic and operational decisions. Using Group Model Building methodology and the software Ithink two models were built, and an important change in the planning process was implemented. The first model, representing the production and debt structure of the Company was created to support long term investment decisions. The second model showing the Company’s financial structure in detail was created to support the annual planning, budgeting activities and to test commercial decisions. The results achieved show how System Dynamics can be used to improve the decision making process and to support the management and the owner learning process.