The main objective of this study was to evaluate what would be the economic and environmental consequences of losing the GMO traits in the U.S. for the major crops of corn, soybeans, and cotton. The first step was to obtain from the literature a range of estimates of the yield loses if we move away from GMO traits in the U.S. The second step was to introduce the yield losses obtained in the first step into a well known CGE model, GTAP-BIO, to quantify the land use and economic impacts of banning GMO traits in the U.S. Our analyses confirms that if we do not have access to the GMO technology, a significant amount of land would need to be converted from other crops, cropland pasture, pasture, and forest to meet the global food demand. The land expansion likely is similar to the entire U.S. ethanol program. Furthermore, induced land use emissions were significantly larger that the corresponding figure for corn ethanol. The price changes for corn were as high as 28% and for soybeans as high as 22%. In general, the price increases for the reference and average cases were higher than those observed previously for biofuel shocks. Food price changes in the U.S. amount to $14 - $24 billion per year. As expected, welfare falls both in the U.S. and globally.