This paper examines the relationship between the maize export prices of the United States and Argentina. The results suggest an asymmetric nature of price adjustment. This could be due to the fact that the maize market is characterized by significant concentration. The larger market share of exports by the United States reflects the influences on export price dynamics. The structure of maize trade is such that U.S. markets are largely insulated from influences flowing from Argentina, while Argentine maize prices are not insulated from U.S. influences.