ENThe article examines the organization of military affairs in the Grand Duchy of Lithuania in the middle of the 18th century. A study of the main prerequisites and directions for the implementation of the military reform in 1764–1766 was carried out. The author comes to the conclusion that as a result of the cautious actions of the Military Commission of the Grand Duchy of Lithuania, positive changes began in the financing of the army, attempts were made to equalize the imbal ance of the officer and rank–and–file personnel in subdivisions, subordination and discipline in the army. However, despite the indicated positive shifts, the most important issues related to the quantitative composition of the army were not resolved. Keywords: military affairs, military reform, army of the Grand Duchy of Lithuania, infantry, cavalry.