The paper is based on the narrative texts Irom medieval Russia and Great Duchy of Lithuania. The theme under study is t,he state and military service ol prince Andrej Mikhajlovich Kurbskiy (1528-1583) during the Livonian War (1558-1583). He began his service in the Russian army, and reached the top of his career. He became a highest rank commander of forces in Livonia and ruler ol Jurjcv, the capital ol Russian Livonia. After his emigration in 156/i he became an ordinary commander in the army of Great Duchy of Lithuania, served in administrative posts, took part in the work of Lithuanian «parliament» (scjm). Kurbskiy was the adviser of Lithuanian diplomatic service and king Simismund in «Russian problem» during the Livonian War.