The purpose of this paper is to discuss the use of simulation as a tool for market performance analysis. A specific application is made to the processing sector of the domestic vegetable oil industry, a highly concentrated sector for which price and cost data are not readily available. Using representative plant and firm models, returns on five products are estimated over time by simulating production and marketing functions at actual input and output prices by months for the period January 1974 through December 1975. The results indicate that market power in the vegetable oil industry was insufficient to generate excessively high returns over this period, and demonstrate the potential of the simulation approach for use in studies of market performance.