Żydowski Związek Wojskowy (ŻZW, Polish for Jewish Military Union) was an underground resistance organization operating during World War II in the area of the Warsaw Ghetto, which fought during the Warsaw Ghetto Uprising. It was formed primarily of former officers of the Polish Army in late 1939, soon after the start of the German occupation of Poland.
Due to the ŻZW's close ties with the Armia Krajowa (AK), which was closely linked to the Polish Government in Exile, after the war the Soviet-dependent People's Republic of Poland suppressed publication of books and articles on ŻZW. Its role in the uprising in the ghetto was underplayed, in favour of the more socialist Żydowska Organizacja Bojowa (Jewish Fighting Organization).
The ŻZW was formed some time in November 1939, immediately after the German and Soviet conquest of Poland. Among its founding members may have been Dawid Mordechaj Apfelbaum (there is some debate as to whether Apfelbaum is a real or fictional person), a pre-war Lieutenant of the Polish Army, who proposed to his former superior, Captain Henryk Iwański, the formation of a Jewish en cadre resistance as an integral part of the general Polish resistance being formed at that time. At the end of December such an organization was indeed formed and received the name of Żydowski Związek Walki. On January 30, 1940, its existence was approved by General Władysław Sikorski, the Polish commander in chief and the prime minister of the Polish Government in Exile.