Mars 5 (Russian: Марс-5), also known as 3MS No.53S was a Soviet spacecraft launched to explore Mars. A 3MS spacecraft launched as part of the Mars programme, it successfully entered orbit around Mars in 1974. However, it failed a few weeks later.

The Mars 5 spacecraft carried an array of instruments to study Mars. In addition to cameras, it was equipped with a radio telescope, an IR radiometer, multiple photometers, polarimeters, a magnetometer, plasma traps, an electrostatic analyser, a gamma-ray spectrometer, and a radio probe. The Three cameras were a 52mm Vega, a 350mm Zulfar and a panoramic camera.

Built by Lavochkin, Mars 5 was the second of two 3MS spacecraft launched to Mars in 1973, following Mars 4. A 3MS was also launched during the 1971 launch window as Kosmos 419. However, due to a launch failure, it failed to depart Earth orbit. In addition to the orbiters, two 3MP lander missions, Mars 6 and Mars 7, were launched during the 1973 window.