The siege of Leningrad (Russian: блокада Ленинграда; German: Leningrader Blockade) was a prolonged military blockade undertaken from the south by the Army Group North of Nazi Germany against the Soviet city of Leningrad (now Saint Petersburg) on the Eastern Front in World War II. The Finnish army invaded from the north, co-operating with the Germans, and completed the ring around the city.

The siege began on 8 September 1941, when the Wehrmacht severed the last road to the city. Although Soviet forces managed to open a narrow land corridor to the city on 18 January 1943, the Red Army did not lift the siege until 27 January 1944, 872 days after it began. The blockade became one of the longest and most destructive sieges in history, and it was possibly the costliest siege in history due to the number of casualties which were suffered throughout its duration. In the 21st century, some historians have classified it as a genocide due to the systematic starvation and intentional destruction of the city's civilian population.