The article examines the relationship between Western Russianism (Zapadnorusizm) and Byelorussian nationalism. Byelorussian nationalism is much younger than Western Russianism, finally shaping only in the end of the 19th century. Before 1917 revolution Byelorussian nationalism could not compete with Western Russianism. The national policy of the Bolsheviks contributed to the decline of Western Russianism and helped Byelorussian nationalism to gain stronger positions. However, Byelorussian nationalists actively cooperated with the occupation authorities during the Great Patriotic war. That caused distinctly negative attitude of Byelorussians towards the movement and collaborators. Currently, Byelorussian nationalism is supported both by the opposition and by the government. Western Russianism has no political representation, but is supported by the majority of Byelorussian populatton.