The expansion of the U.S. corn seed trade is not well understood. This article econometrically investigates world demand for U.S. corn seeds, focusing on trade costs impeding exports, including transportation, tariffs, and sanitary and phytosanitary (SPS) regulations. The analysis estimates a derived demand for seed by foreign corn producers using data from 48 countries for the years 1989 to 2004. An SPS count variable captures shifts in the cost of seeds faced by foreign users. A sample selection framework accounts for the large presence of zero trade flows. All trade costs have a significantly negative impact on U.S. corn seed exports.