The centenary of the Comintern is a significant reason to analyze the mechanisms, forms and results of the Comintern influence to the formation of left-wing forces. The communist movement in Latin America, including Uruguay, was formed under the influence of the III (Communist) International. This article shows how the traditions of organization of party work, ideology, programs formed by the Comintern continue to have a significant impact on the life of the modern Uruguayan left movement, the Communist Party and trade union organizations.