When in 1929 the world economy went into crisis, a new approach to international trade and finance appeared on the scene. Characterised by bilateralism, protectionism and autarchy, this approach challenged the idea of liberal free trade. Its main proponents were Nazi Germany and Fascist Italy. This thesis is about the role of economic factors in the German-Italian rapprochement under the banner of the fascism. The analysis looks with an institutional approach at three levels: the formulation of foreign economic policies, the implementation by governments, and the execution at the level of businesses. Not only is the bilateral German-Italian commercial relationship analysed, but also co-operation and rivalries between German and Italian government officials, economic experts and business representatives in third-party markets, as well as international organisations (especially the League of Nations) dealing with the crisis. The thesis shows that the "Rome-Berlin Axis", which plunged Europe and the world into the disaster of World War II, was built on economic foundations with serious cracks. Admittedly, Germany's and Italy's mutual economic importance increased notably, while they foreclosed their markets to former trade partners (especially the US). However, the analysis of the institutions governing the trade and its detailed structure indicate without question that this rapprochement followed no economic logic. Germany needed political support for its revisionist plans for Europe and was willing to pay for it. Nevertheless, in third-party markets no concessions were made. Especially in Southeastern Europe and the Eastern Mediterranean, Nazi Germany harvested what Fascist Italy had sown. To increase market shares, Berlin copied foreign economic policies, developed by the likewise financially strapped Italy. Opportunities for better economic collaboration were given away. Victims of the approach can be found in many areas (e.g., chemicals, cars, artificial fibres) and especially among cross-border business endeavours. The contradictions in the economic rapprochement of the interwar ultra-nationalistic regimes clearly demonstrate the limits of economic nationalism in a globalising world.