Progress 31 (Russian: Прогресс 31) was a Soviet uncrewed Progress cargo spacecraft, which was launched in August 1987 to resupply the Mir space station.

Progress 31 launched on 3 August 1987 from the Baikonur Cosmodrome in the Kazakh SSR.

[2][4] Progress 31 docked with the aft port of the Kvant-1 module of Mir on 5 August 1987 at 22:27:35 UTC, and was undocked on 21 September 1987 at 23:57:41 UTC.

[3][5] It remained in orbit until 23 September 1987, when it was deorbited.

[3][5] This article about one or more spacecraft of the Soviet Union is a stub.