A hilarious running race saw dozens of schoolkids making a mad dash - all dressed in Tyrannosaurus Rex costumes.

The event occurred at the Emerald Downs Race Course in Auburn, Washington State, USA, for the annual 'world championship T-Rex race'.

Children participated in the 14-and-under competition in various heats to find themselves in the final.

Dozens of kids are seen sprinting in their hilarious costumes to the finish line.

Emerald Downs posted online: "We are expecting a 200-300 T-Rexes for the races."

"All T-Rexes get in free with costume."

"This is the The biggest T-Rex race in the world. Who will be the fastest T-Rex?"

"The races will occur during the Thoroughbred races, after horse races 2, 4 and 6."

"Races will be contested for Kids 14-and-under heat races for everyone else. The winners of each heat race will qualify for the T-Rex World Championship."

The footage was captured on August 20.