At the time of its first flight on 26 December 1982, the An-124 was the largest aircraft in the world. Antonov's experience with the huge turboprop An-22 gave it a head start when design began on the new giant, as did knowledge of the slightly smaller Lockheed C-5 Galaxy. Indeed, apart from its low-set tailplane, the An-124 is very similar to the Lockheed product.

Four Lotarev D-18T turbofans power the giant, slung in pods under the large anhedralled wing. Full-span leading-edge slats and large flaps give the An-124 impressive short field capability, while its 20 main wheels allow the type to use rough fields. Two nose-wheel units each have a pair of wheels, and these can be retracted on the ground allowing the aircraft to 'kneel' to assist loading. Like the Galaxy, the An-124 has an upward-hingeing nose visor and rear clamshell/ramp doors to allow front or rear drive-on loading.

Accommodation on the flight deck caters for six crew (two pilots, two engineers, a navigator and a radio operator), and behind this is a rest area. Behind the wing on the upper deck is accommodation for up to 88 passengers. The 36m long main cabin is pressurised and has two electric cranes in the roof, each lifting up to 20000kg. Two winches are fitted, able to pull loads through the cabin. Control of the aircraft is effected by a quadruple-redundant fly-by-wire system.

Following its first flight, with Vladimir Terski at the controls, the An-124 showed few problems, and production aircraft appeared quickly. The second aircraft, named Ruslan, appeared at the 1985 Paris Air Salon. The aircraft entered service with Aeroflot in early 1986, and now serves principally on the Siberian run, carrying outsize items to the oil and mineral exploitation industries. In 1987 the An-124 began service with the air force. Production is reportedly eight to ten aircraft per year, and by 1989 over 25 had been completed. The An-124 was assigned the NATO reporting name 'Condor'.