The Leningrad Affair ("Ленинградское дело" in Russian, or Leningradskoye delo), a series of "criminal" cases, fabricated in the late 1940s–early 1950s in order to accuse a number of prominent members of the Communist Party of the Soviet Union of "treason" and "intention" to create an anti-Soviet organization out of the Leningrad Party cell.

As a result, in 1950, Nikolai Voznesensky , Mikhail Rodionov , Aleksei Kuznetsov , Pyotr Popkov , Ya.F.Kapustin and P.G. Lazutin were sentenced to death. The rest of the "accomplices" were sentenced to different prison terms. Simultaneously, the Soviet authorities replaced party and administrative leadership in Leningrad.

All of the accused would later be rehabilitated, most of them posthumously.