The Trial of the Sixteen was a staged trial of 16 leaders of the Polish Underground State held by the Soviet authorities in Moscow in 1945. All captives were kidnapped by the NKVD secret service and falsely accused of various forms of 'illegal activity' against the Red Army.

The Polish Underground State [a] was a single political and military entity formed by the union of resistance organizations in occupied Poland that were loyal to the Government of the Republic of Poland in exile in London. The first elements of the Underground State were established in the final days of the German and Soviet invasion of Poland, in late September 1939. The Underground State was perceived by supporters as a legal continuation of the pre-war Republic of Poland that waged an armed struggle against the country's occupying powers: Nazi Germany and the Soviet Union. The Underground State encompassed not only military resistance, one of the largest in the world,[b] but also civilian structures, such as justice, education, culture and social services.