The left-wing movement remains one of the leading political forces in Uruguay. In recent years, the spectrum of left-wing forces has expanded, new ultra-left parties, an ecological movement was formed, anarchist and Marxist groups continue to work. During the 20th century, the ideology of the Uruguayan left has changed under the influence of both internal and external factors. One of the factors in the formation of the ideology of the left movement of Uruguay was the Comintern. This article shows how the Communist International influenced to the political theory and practice of the Uruguayan left. Based on the analysis of archival materials - party programs, documents of the Comintern, newspapers, letters and reports about left movement - the article shows the influence of the "world communist party" on the strategy and tactics of the left forces, the peculiarities of their organization, agrarian, youth, trade union programs.