The Rh-202 is an early Cold War era 20mm autocannon of German origin. It was developed in the 1960's by Rheinmetall as a limited weight weapon system that could provide a high volume of fire. The design has proven to be very capable and has been used in a wide variety of applications. The Rh-202 is also well known under is German service designations MK 20, which is short for Machinenkanone 20 .

The Rh-202 is a gas operated weapon with a rather high rate of fire. The recoil forces are reduced by a muzzle brake and the design principle of firing a round before the previous recoil phase is completed. A single and double belt feed model are available. For vehicle applications the double feed is common in order to rapidly switch between armor piercing and high explosive rounds. For anti-aircraft use only high explosive rounds are required.

The Rh-202 fires the common 20x139mm NATO round for which a wide variety of ammunition types are available. The Rh-202 can fire single shots or automatic fire at 880 to 1.020 rpm. The effective range is 2 km while the slant range for high explosive rounds is about 4 km. The 20x139mm round is effective against infantry, softskin and light armored vehicles and nearby aircraft. More heavily armored vehicles such as mechanized infantry combat vehicles and light tanks are usually resistant against the 20x139mm round.

The Rh-202 is used for a variety of applications. The most common use is on the Marder mechanized infantry combat vehicle, but also on many other vehicles including the Luchs, Tipo 6616 and Wiesel reconnaissance vehicles. The Rh-202 is also used in a similar named towed twin anti-aircraft gun and on single gun pedestal mounts on navy ships.