The article deals with the problematic of the Czech language changes in 20th century. The main attention is given to problematic of the Czech lexicon changes under the influence of historical turns in this century. 20th century was the time of the Czech lexicon dynamical changes, because political, technical and cultural development of the Czech society was very fast and rich. The most interesting historical events, that produced significant part of these changes, was the fall of Austrian Habsburgs empire in the 1918 and the establishment of Czechoslovak democratic state and society in the 1920s and 1930s, the occupation of Czech countries by German forces in the 1939-1945, the establishment of Communist Party government in the end of 1940s and 1950s and the Czech society democratic transformation after the 1989s “Velvet” Revolution. Historical turns are focused on the Czech standard and substandard lexicon. Lexical changes were realized especially in the group of substantives (appellatives and proper substantives) and verbs. The great part of these lexical changes were motivated by German, French, English and Russian languages.