Transnational companies are the key drivers of foreign direct investments and major actors in international trade. They are involved in more than two-third of international trade and determine its direction, composition and volume. The relationship between transnational companies and international trade is complex and interwoven, raising the following question: are transnational companies substitutes or complements of international trade? The author explores this relationship. She studies the role of these companies in international trade as a whole and in foreign trade of domestic and host countries.