Jockey Brian Toomey suffered life-threatening injuries after falling from his horse at Perth Racecourse.
Mr Toomey was riding the favourite Solway Dandy in the conditional jockeys handicap hurdle when he fell badly at one of the last hurdles on Thursday.
An air ambulance was immediately called to the scene before it was decided to take Mr Toomey to hospital by road, a Scottish Ambulance Service spokeswoman said.
Witnesses suggested the Yorkshire-based jockey had lost consciousness and paramedics had to help his breathing. He is in intensive care at Ninewells Hospital, Dundee, with life-threatening head injuries.
Sympathy and well wishes for Mr Toomey, who has won 49 hurdle races since 2008, flooded social media after news of his injury spread.
Champion jockey AP McCoy tweeted: “Thoughts and prayers are with Brian Toomey who had a very serious fall at Perth today. Let’s hope he will be OK,”
Grand National and Gold Cup winning jockey Mick Fitzgerald added: “Fingers & everything else crossed for Brian Toomey. In intensive care, thoughts are with him & his family.”
Jockey Richard Killoran tweeted: “All thoughts with Brian Toomey at this moment. Lets pray for him.”