Soyuz 34 was a 1979 Soviet uncrewed space flight to the Salyut 6 space station. It was sent to supply the resident crew a reliable return vehicle after the previous flight, Soyuz 33, suffered an engine failure.

Mission control decided to re-design the engine used on Soyuz craft as a result of the Soyuz 33 failure, and to return the Soyuz 32 craft which transported Vladimir Lyakhov and Valery Ryumin to the space station to earth uncrewed as it had the same suspect engine as Soyuz 33. Soyuz 34 successfully returned the crew to earth 73 days after launching.

This is Soyuz's 52nd flight, and 33rd crewed flight.

The Soyuz is a Soviet crewed spaceship, developed to made manned lunar missions. This version called 7K will fly 4 times on the giant launcher N1, and several tens of times on Proton to fly over the Moon, which will be successful during the mission Zond 4. Soyuz will become the first spacecraft to transport living beings to the Moon during the flight of Zond 5, with two turtles. Subsequently, it is adapted to low orbit and will fly on the Soyuz launcher to serve the Salyut and Mir stations and the ISS.