The article deals with Finnish translations of varieties of spoken language in fiction from the late 19th century to the beginning of the 2000s. It presents the central findings of a comprehensive study on the changes and developments of translational norms in Finnish literature. The study is based on a corpus consisting of 200 literary works (the original and its translations are counted as one work), representing various genres: literary fiction, young-adult fiction, as well as genre fiction (romance and crime). During this 100-year period, the use of colloquial variants in translations has strongly increased, influenced by the changing literary and linguistic norms of original Finnish literature. The norms of different literary genres, however, vary, and rich, non-standard variation can be found in translated works from different periods.