Blue Peter's Matt Baker, Olympic athlete Sally Gunnell and DJ Sara Cox are among celebs ready to step into the saddle to raise money for Sport Relief.
The fearless stars will learn how to be professional show-jumpers after just a couple of weeks training.
Starting on 7 July competitors - some of whom have never even ridden a horse before - will take part in a nine-day "jump off" in front of a live audience.
The final will take place on the BBC's Night of Sport Relief on 15 July.
During the competition the trainees will live at stables in Essex. They will be expected to take part in all aspects of looking after the horses - including mucking out!
Cash raised by Sport Relief will be split between helping people in the UK and those in some of the world's poorest countries.