Since the last decade, significant changes have occurred in the trade flows of agri-food products of the Southeastern European countries (SEE) due to adjustment to international market. Namely, as all countries of the SEE strive to be full members of the EU; market opportunities have been changing, primarily because of the reduced barriers on trade with the EU, as well as with the regional countries. In order to investigate the effects of the liberalization process of the agri-food sector of the SEE countries on their export, as well as the total foreign trade, a gravity model based on panel data in the period 2005–2015 has been estimated. According to the results, liberalization of the market in the SEE countries, as a consequence of the EU enlargement process, as well as regional integrations, had positive effects on the total foreign trade of agri-food products. Despite the positive liberalization effects on the agri-food trade, all SEE countries have a lower level of competitiveness than the EU countries, so an organized access to products which possess comparative advantages will be an important condition for the achievement of their particular positions at the international market.