ENThe coup d'etat of December 17, 1926 was a turning point in the history of Lithuania, thus parliamentarism was changed by an authoritarian regime which lasted until the occupation and annexation of 1940. The Soviet historiography on the coup and authoritarian power of nationalists is rather extensive, however, the relevant definitions formulated in the Communist Party's documents of 1926 became unquestionable and compulsory. During the years of Independence the illegal Communist Party Central Committee referred to these definitions in their regulations, proclamations and other publications. V. Mickevičius-Kapsukas in his book „Bourgeois Lithuania" published as late as 1961 defined the Communist approach in a very particular way. The coup was described a fascist and the national government as „a power of fascists - open bourgeois dictatorship". The blame was also put on the Social Democrats and Peasant-Nationalists. The terms and definitions that appeared in a very descriptive and subjective book of V. Kapsukas came into use in the Lithuanian Soviet historiography until 1989. The same applies to the Lithuanian SSR historical studies of the end of the 50's and 60's, but the scientific level of e.g. E. Dirvelė papers was higher, at least formally. One can find fewer primitive evaluations and stamps in the studies of Lithuanian Soviet historians of 70's. It can be accounted for by a more liberated intellectual atmosphere as well as a slight but noticeable disentanglement of the Soviet history science from dogmatism. Nevertheless, the release was rather restricted. This can be witnessed by the discussion on the I. Lempertas' book „Fascist regime in Lithuania" as well as by the attack of the journal „Communist" on the historian M. Tamošiūnas who expressed his doubt whether the national government could be reasonably called as a fascist one.Though no administrative actions were taken against M. Tamošiūnas the government didn't allow the Soviet Lithuanian historians to revise the terms such as „fascist coup", „fascist regime" even referring to the Marxist methodology itself. It can be assumed that the Central Committee ideologists of the Lithuanian Communist Party followed these stamps not only from the point of view of their ideology but most often because of pragmatic reasons. The occupation and annexation of 1940's seemed to be more legitimate if they put an end to „fascist regime" which came to power as a result of the fascist coup d'etat. The works of historians couldn't contradict but background the postulations of the Communist party.