This article includes the world record progression for the 4×50 metres medley relay and it shows the chronological history of world record times in that competitive short course swimming event.
FINA amended its regulations governing the recognition of world records in 1956; specifically, FINA mandated that only record times that were contested in 50-metre (or 55-yard) pools were eligible for recognition after that time.
[2] In October 2013 FINA decided to establish "standards" before something can be recognized as the first world record in these events.
[3] But later on March 13, 2014, FINA has officially ratified the eight world records set by Indiana University swimmers at the IU Relay Rally held on September 26, 2013, in Bloomington.
[5] Swimming the other three legs of the medley relay cannot qualify as world records as FINA criteria require a "static start" for world record recognition – swimming relay exchanges are characterized as "dynamic".