Controversy surrounds the introduction of genetically modified foods. One key issue relates to tolerance levels-the impurity rate tolerated before a commodity must be labeled. Currently, the United States has not defined a tolerance level for genetically modified foods. This paper uses data from experimental auctions to test whether consumers prefer foods with 0, 1, or 5% tolerance levels for genetically modified material. We conclude consumers would pay less for food that tolerates genetically modified material, but find no evidence that consumers' place different values on foods with 1 and 5% genetically modified content.