The economic feasibility of soybean and sunflower crop system on a farm in Diamantino MT Brazil is analyzed. Data were retrieved from the 2017-2018 harvest, even though they were repeated for a six-year span. Project-inherent items were grouped in fixed and variable costs. Main financial indexes comprised total yearly income, current net rate, equivalent uniform yearly rate, internal rate of return, profit index during the period and payback period. In the case of the suggested system, the plantation proved to be viable, with total yearly income of R $3,624,000.00 at the end of six years; current net rate at R $1,468,920.00; equivalent uniform yearly rate at R $334,810.00; 18% internal rate of return; 33% profit index during the period, and payback period of 4.53 years. However, 15% negative variations in price, productivity or income, or positive variation at 30% in real operation costs proved the unfeasibility of the project, with special reference to current negative