Sheikh Fahad Al Thani suffered cuts to his head and face after he was unseated in an eventful running of the historic Newmarket Town Plate.
The leading owner-breeder, who heads Qatar Racing, was bidding to win the prize second year running when he came off Alamagest ,at the two-furlong pole.
Sheikh Fahad was contesting third place and appeared to be coming with a late challenge when he lost balance and fell off on top of the stands rails, crashing through them
An ambulance was on the scene swiftly to attend Sheikh Fahad who was taken to the racecourse medical room for examination.
Riders who took part in the race said a piece of equipment may have come loose or broken, and Sheikh Fahad later confirmed the saddle had slipped.
Trainer Michael Mullineaux, who rode the third-placed Drivehomeregardless, said: "He was on my outside and his reins were like washing lines so I decided to take a tug. In the next 50 yards his horse went to the rail and something flipped off.
The 348th running of the the 3m6f contest for amateur riders was won by the Tim Gredley-ridden, Bivouac.
In a dramatic race Keith Oakes was unshipped after the line from Bell Weir but was unscathed.
Sheikh Fahad is an enthusiastic rider and experienced a notable success last year in a Leopardstown charity race on subsequent Supreme Novices' Hurdle winner Labaik.
He also participated in the Mongul Derby getting past halfway in what is regarded as the longest, toughest horse race in the world.