Tetrathlon is a modified version of the Modern Pentathlon, composed of 4 out of the 5 disciplines of Modern Pentathlon. There are different versions of the tetrathlon, comprising a different set of four events

The Tetrathlon events held by the international governing body of modern pentathlon (UIPM, Union Internationale de Pentathlon Moderne) comprises the individual events of swimming, running, shooting and fencing (no equestrian events). All four events take place on the same day. The winner is the athlete with the most points accumulated from each event.

There are also tetrathlon events held by pony clubs, which comprise the four disciplines of shooting, swimming, riding and running (there is no fencing). The competition is commonly held between teams of four members from one pony club competing against other clubs. Competitions are usually held over two days.