The discus throw is an event in track and field competition, in which an athlete throws a heavy disc — itself called a discus — in an attempt to mark a farther distance than his or her competitors. It is an ancient sport, as evidenced by the 5th century BC Myron statue, Discobolus. Although not part of the modern pentathlon, it was one of the events of the ancient pentathlon, which can be dated at least back to 708 BC.

A routine part of most modern track and field meets at all levels, it is a sport which is particularly iconic of the Olympic Games. The men's competition has been a part of the modern Summer Olympic Games since the first Olympiad in 1896. Images of discus throwers figured prominently in advertising for early modern Games, such as fund raising stamps for the 1896 games and the main posters for the 1920 and 1948 Summer Olympics.

The women's competition was added to the Olympic program in the 1928 games, although they had been competing at some national and regional levels previously.

The discus, the object to be thrown, is a heavy lenticular disc with a diameter of 220 mm (8.66 inches) and a weight of two kilograms (4 lb 7 oz) for the men's event, and a diameter of 181 mm (7.17 inches) and a weight of one kg (2 lb 3 oz) for the women's event. In U.S. high school track and field, boys typically throw a discus weighing 1.616 kg (3 lb 9 oz) and the girls throw the 1 kg (2.2 lb) women's disc. The discus can be thrown starting at age 11 (midget division). Most children throw the 1 kg discus. The discus usually has sides made of rubber, plastic, wood, or metal with a metal rim and a metal core to attain the weight. A discus with more weight in the rim produces greater angular momentum for any given spin rate, and thus more stability, although it is more difficult to throw. A practice discus made of solid rubber is often used in High School; it is cheaper, more durable, and easier to learn to throw (due to its more equal distribution of weight, as opposed to the heavy rim weight of the metal rim/core discus).

To make a throw, the competitor starts in a slightly recessed concrete-surfaced circle of 2.5 meters (8 feet 2½ inches) diameter. The thrower typically takes an initial stance facing away from the direction of the throw. He then spins around one and a half times through the circle to build momentum, then releases his throw. The discus must land within a 40-degree or 60-degree arc marked by lines on the landing zone, and the competitor must not exit the circle until the discus has landed, then must wait for the judge to give clearance to exit the ring from the rear half. The distance from the front edge of the circle to where the discus has landed is measured, and distances are rounded down to the nearest centimeter or half-inch. The competitor's best throw from the allocated number of throws, typically three to six, is recorded, and the competitor who legally throws the discus the farthest is declared the winner. Ties are broken by determining which thrower has the longer second-best throw.

The basic motion is a fore-handed sidearm movement. The discus is spun off the index finger or the middle finger of the throwing hand, spinning clockwise when viewed above for a right-handed thrower, and vice-versa. As well as achieving maximum momentum in the discus on throwing, the discus' distance is also determined by the trajectory the thrower imparts, as well as the aerodynamic behavior of the discus. Generally, one wishes to throw into a moderate headwind to achieve maximum throws. Also, a faster-spinning discus imparts greater gyroscopic stability. The technique of discus throwing is quite difficult to master and needs lots of experience to get right, thus most top throwers are thirty years old or older.

A common technique employed by younger people is to not spin at all, but to jump forward a step to gather momentum. Although it doesn't provide as much power, it is easier to do.

Despite the long association of the discus with the Olympics, the Games have only twice produced a world record. In the inaugural men's event in Athens, American Bob Garrett overcame an earlier world record-setting throw by Panagiotis Paraskevopoulos to win the gold. Similarly, in the first women's event in 1928, Polish thrower Halina Konopacka set a world record in the event.

Since these initial performances, however, world records have only been set outside Olympic venues.