The link between international trade, animal health and epidemiology has been recognized for a long time and has taken an additional importance in the aftermath of the Uruguay Round of Multilateral Trade Negotiations of the General Agreement on Tariffs and Trade (GATT) and of the inception of the World Trade Organization. The Agreement on the Application of Sanitary and Phytosanitary Measures of the World Trade Organization demands that sanitary and phytosanitary measures be scientifically based, placing epidemiology at the center of decisions related animal health and trade. This paper analyses the interactions between international trade of animals (and animal products) and epidemiology with discussion on the inputs of epidemiology in surveillance, risk analysis and regionalization.