Not all trade barriers concern steel, corn and coffee. Major human semen exporters like the United States say they are having a hard time penetrating Mexico's sperm market. Human semen trade is an estimated US$100 million industry worldwide, but Mexico is abstaining from entering the market and using its own internal resources. Mexico has not banned the imports outright; however, strict federal standards and restrictions keep foreign semen out of the country. The Fertility Institutes, a semen supplier with offices in both the United States and Mexico, has been unable to swap semen across the border among its clinics. "Not because of a lack of need or desire, but because of the inability to meet all requirements of both countries, as well as FedEx and other international shippers," says Fertility Institutes' Jeffrey Steinberg. Meanwhile, strong demand in Canada for human semen on recent years--which sells for about the same price as cattle semen in the open market--eased border restrictions for sperm imports from the United States. Leading U.S. semen trader Xytex has shipped its U.S. genes to Canada and several countries in Europe since 1983, but the company says getting across its southern border poses a much bigger challenge. "It's virtually impossible," says Holly Fowler, spokesperson for Xytex. Foreign exporters trying to ship their specimen into Mexico apparently must overcome the country's main barrier to entry into the sperm market: national pride.