This study estimates demand for wheat differentiated by classes using a dynamic AIDS model for the United States and the European Union (EU). The results suggest that imported wheat is more price responsive than domestic wheat in the U.S. market but not in the EU market. This may suggest that the Canadian policy that reduces prices of Canadian wheat in the U.S. market or U.S. export subsidies that raise prices of U.S, wheat could be expected to give rise to substantial substitution of Canadian for U.S. wheat. It is also found that in the EU, complementary relationships exist between spring and other wheat groups, This complementary relationship between the lower and higher quality wheat in the EU is not surprising because EU millers blend cheaper wheat such as EU common wheat and U.S. other wheat with high protein (spring) to obtain the preferred characteristics.