A bioeconomic approach was used to evaluate random variation of growth and mortality parameters and feed conversion ratio (FCR) for intensive production of the blue shrimp Litopenaeus stylirostris (Stimpson). Severe mortality problems caused by high impact diseases were not considered in this analysis. For a 50-ha farm, the maximum values of the internal rate of return (IRR 5 44%) and net revenue above operation costs (NR 5US$1211000) were obtained for a stocking density of 67 postlarvae (PL) m À 2 during winter^spring (cycle 1) and 65 PL m À 2 during summer^autumn (cycle 2). Regardless of the density used for cycle 1, stocking at 50 and 65 PL m^2 for cycle 2 su⁄ced to obtain, respectively, IRRs greater than the minimum attractive IRRs of 15% and 30%. A frequency distribution of IRR, projected for densities of 67 and 65 PL m À 2 , showed high con¢dence in obtaining IRR values above 15% and 30% (i.e. con-¢dence 499% and 92% respectively). The frequency distribution of NR showed that the farm could operate without economic losses. Stocking a minimum of 53% of the capacity of the farm would guarantee positive NR. Sensitivity analysis indicated that the IRR and NR were mainly in£uenced by mortality rate, selling price, density, ¢nal weight and FCR.