Companies have been present in the sphere of international business for hundreds of years. The main aim of this article is to show that there are still many problems with defining what the multinational or transnational company is and how to measure the level of its internationalization. The article is mainly based on the analyzed information from books and articles dedicated to this subject. From the theoretical point of view, the main problem is that although many indices of internationalizion have been developed so far, including synthetic ones, like the TNI index proposed by the UNCTAD, scientists still have real problems with preparing indices which would be at the same time synthetic and incorporating relevant and practically used information on the companies’ activities across countries.

Companies have been present in the sphere of international business for hundreds of years. The main aim of this article is to show that there are still many problems with defining what the multinational or transnational company is and how to measure the level of its internationalization. The article is mainly based on the analyzed information from books and articles dedicated to this subject. From the theoretical point of view, the main problem is that although many indices of internationalizion have been developed so far, including synthetic ones, like the TNI index proposed by the UNCTAD, scientists still have real problems with preparing indices which would be at the same time synthetic and incorporating relevant and practically used information on the companies’ activities across countries.