The RKG-3 is an anti-tank grenade of Soviet origin. The RKG-3 was developed to replace the variety of anti-tank grenades that were developed during World War 2. It entered service after World War 2 and has seen widespread use during the early phases of the Cold War. The RKG-3 was one of the last anti-tank grenades to be designed as rocket launchers have become the primary infantry weapon for engaging armored vehicles. The name RKG stands for Ruchnaya Kumulyativnaya Granata, Russian for shaped charge hand grenade.

The RKG-3 has the same layout as its predecessors. It consists of a shaped warhead on a stick. A four paneled fabric drogue is folded into the stick and is released by a spring. The drogue makes sure that the shaped warhead is pointed in the direction of the armor. It makes it also possible to throw the grenade in an arc on top of the weaker roof armor of the target. When the safety pin is removed and the grenade is thrown the spring pushes the drogue out of the stick. The pull disconnects the internal safety device and arms the warhead. The warhead is set off instantaneous on impact.

The penetration of the RKG-3 series is much better than the previous RPG-43, RPG-42 and RPG-6 and will penetrate 125 to 165mm RHA depending on the version. Due to its weight and method of operation the throwing range is only 15 to 20 meters. The fragmentation effect has a range of 20 meters. Therefore it is necessary to find cover immediately after throwing the grenade. The RKG-3 can also be used against infantry. The blast has a lethal radius of about 2 meters, but the fragmentation effect can reach out to 20 meters. Although the RKG-3 produces the same fragmentive effect as a fragmentation grenade it is less reliable and effective while the fragments are not scattered in all directions.

In Russia, China and Eastern Europe the RKG-3 replaced all previous anti-tank grenades. Only the RPG-6 was sometimes retained to be used as a life training round or for use against infantry. In the rest of the world, especially the Middle East and Asia, it was used in large numbers besides other anti-tank grenades. The RKG-3 and its variants were used extensively by the Arab forces in the 1973 October War. For many years the RKG-3 is no longer in production and with the widespread use of rocket launchers such as the RPG-7 there is no need for anti-tank grenades anymore.