This article considers the economic optimal carry-over stocks of maize. A simulation model that calculates total inventory costs at given stock levels for both white and yellow maize, is described. The model takes both holding costs and out of stock costs, as well as the variability of maize production and uncertain demand for maize, into account. Structural adjustments and maize prices are explicitly accommodated to accentuate structural changes and the role of prices. Results show that the present total maize carry-over stocks of 900 kt per annum are near the optimum. The relative importance of white maize to yellow maize should however increase.