The lumbering IS-3 missed out combat in the European Theater of World War II by a matter of weeks, although one unit was involved during the Soviet invasion of Manchuria during the final stage of the war in the Pacific. It shared little resemblance with the IS-2, featuring instead a rounded cast turret and more pronounced slope on the glacis plate. Armor protection was also stepped up significantly, although at a cost of greater weight. It did retain share the IS-2’s massive 122-mm gun, the largest fitted on a World War II tank, with provision for both armor-piercing and high-explosive rounds. Despite its impressive specifications, the IS-3 suffered from the same limitations as most tanks of its size, mainly slow speed and mechanical unreliability and as a result, was replaced by the new generation of main battle tanks by the 1960s. In Soviet service, the IS-3 had limited combat experience, featuring only during the invasions of Hungary (1956) and Czechoslovakia (1968). It was, however, exported to China and Egypt, the latter which used it during the Six-Day war where its frontal armor was shown to be invulnerable to Israeli M48s. A few captured units were later modernized and placed in Israeli service.

Development of the IS-3 (Ob’yekt 703) began in late 1944 and entered service the following year. It received numerous modifications over the years, such as improved radio equipment and new road wheels. A more thorough modification program in the 1960s resulted in the IS-3M, of which the most prominent external change was the installation of sideskirts. Around 100 of these were provided to Egypt.