In the aftermath of World War I, patriotic organisations and right-wing armed groups multiplied both in Europe and in Northern and Southern America. This article deals with the history and activities of the main patriotic leagues then arising in Latin America, and takes in particular account the most important and long-lasting, the Liga Patriótica Argentina. Very often aided by governments and armed forces, these organisations aimed at disseminating "patriotic" propaganda and at countering the revolutionary threat of the political left and of workers' movements. Despite their intense nationalism, leagues acting in different countries tried to build ties with each other - a rudimentary attempt to create a nationalist international. The Liga Patriótica Argentina was very eager in promoting international co-operation, but did not succeed in creating long-lasting links with "sister" Chilean and Brazilian organisations. When the most intense period of workers' militancy ended, both the reason of being of these leagues and the need for a nationalist international ceased.