Soyuz T-4 was a Soviet space mission which launched the crew of Salyut 6 EO-6, the sixth and final long-duration crew of the Salyut 6 space station. It was launched on 12 March 1981 and docked with the station the next day. During their stay, the EO-6 crew was visited by Soyuz 39 and Soyuz 40. Soyuz T-4 returned to Earth on 26 May 1981; its crew were the last to have inhabited Salyut 6.

This is Soyuz's 59th flight, and 40th 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.