Ramon Dominguez, a three-time Eclipse Award winner as the leading jockey in North America, retired on Thursday due to a head injury suffered in a fall earlier this year.
The 36-year-old Venezuelan fractured his skull during a spill in New York in January when his mount clipped heels with another horse.
"While I hoped and even expected to be able to return to the saddle, as a result of my injuries and upon the advice of my treating physicians, it has been determined that I will no longer be able to pursue my career as a jockey," he said in a statement."
Dominguez never won a Triple Crown race but did reach the winner's circle in three Breeders' Cup races, the Turf in 2004 and 2012 and the Juvenile in 2011.
"Ramon Dominguez leaves an indelible mark on Thoroughbred racing and his profession," NTRA president and CEO Alex Waldrop said in a statement. "Above all, he epitomizes sportsmanship and professionalism as demonstrated by the respect he earned from his fellow jockeys. He is destined for Thoroughbred racing's Hall of Fame."
Over the course of his career, Dominguez won 4,985 races and total race earnings of more than $191 million, including a record $25,582,252 for the 2012 season.
"Ramon's accomplishments - including the last three Eclipse awards as North America's top jockey - only tell part of the story. He has epitomized class both on and off the racetrack," said New York Racing Association vice president P.J. Campo.
Information from Reuters was used in this report.