Although most Jews in Europe were caught inside the Nazi extermination program, some Jews were in a position to resist and fight the Nazis. Jewish partisans were fighters in irregular military groups participating in Jewish resistance movements against Nazi Germany and its collaborators during World War II.

A number of Jewish partisan groups operated across Nazi-occupied Europe, some made up of a few escapees from the Jewish ghettos or concentration camps, while others, such as the Bielski partisans, numbered in the hundreds and included women and children. Partisan groups were most numerous in Eastern Europe, but groups also existed in occupied France and Belgium, where they worked with the local resistance. Many individual Jewish fighters also took part in the other partisan movements in other occupied countries. In all, the Jewish partisans numbered between 20,000 and 30,000.

The partisans engaged in guerrilla warfare and sabotage against the Nazi occupation, instigated ghetto uprisings and freed prisoners. In Lithuania alone, they killed approximately 3,000 German soldiers. They sometimes had contacts within the ghettos, camps, and Jewish councils, and with other resistance groups, with which they shared military intelligence.

In Eastern Europe, many Jews joined the ranks of the Soviet partisans: throughout the war, they faced anti-Semitism and discrimination from the Soviets and some Jewish partisans were killed, but over time, many of the Jewish partisan groups were absorbed into the command structure of the much larger Soviet partisan movement.

The Jewish partisans had to overcome great odds in acquiring weapons, food, shelter and evading capture. They typically lived in underground dugouts called zemlyankas and camps in the forests. Nazi reprisals were brutal, as they employed collective punishment against their supporters and the ghettos from which partisans had escaped, and often used "anti-partisan actions" as a guise for the extermination of Jews. In some areas, partisans were supported by local villagers, but due to widespread anti-Semitism and fear of reprisal, the Jewish partisans were often on their own.

The partisans operated under constant threat of starvation. In order to survive, Jews had to put aside traditional dietary restrictions. While friendly peasants provided food, in some cases food was stolen from shops, farms or raided from caches meant for German soldiers. As the war progressed, the Soviet government occasionally airdropped ammunition, counterfeit money and food supplies to partisan groups known to be friendly.

Those who managed to flee the ghettos and camps had nothing more than the clothes on their backs and their possessions often were reduced to rags through constant wear. Clothes and shoes were a scarce commodity. German uniforms were highly prized trophies: they were warm and served as disguises for future missions.

Those who were wounded or maimed or fell ill often did not survive due to the lack of medical help or supplies. Most partisan groups had no physician and treated the wounded themselves, turning to village doctors only as a last resort.

The forests also concealed family camps where Jewish escapees from camps or ghettos, many of whom were too young or too old to fight, hoped to wait out the war. While some partisan groups required combat readiness and weapons as a condition for joining, many noncombatants found shelter with Jewish fighting groups and their allies. These individuals and families contributed to the welfare of the group by working as craftsmen, cooks, seamstresses and field medics.

Some of the best-known Jewish partisan groups were the Bielski partisans who operated a large "family camp" in Belorussia (numbering over 1,200 by the summer of 1944), and the United Partisan Organization which attempted to start an uprising in the Vilnius Ghetto in Lithuania and later engaged in sabotage and guerilla operations.