Chris Froome was taken to hospital on Wednesday following a crash before stage four of the Criterium du Dauphine.
Team Ineos confirmed in a statement that the four-time Tour de France winner had come off his bike during a reconnaissance of the day's ride and had withdrawn from the race.
Froome was eighth in the overall classification after three stages of the eight-day race, just 24 seconds behind leader Dylan Teuns.
The 34-year-old was using the race in Roanne, France, as part of his build-up to the Tour, which starts on July 6.
In a short statement on their Twitter account, Team Ineos said: "Team Ineos can confirm that Chris Froome crashed during a recon of stage four of the Criterium du Dauphine today.
"He is currently on his way to a local hospital and won't start today's fourth stage. We will provide a further update in due course."
The Tour is only three and a half weeks away and Froome's preparations this season have been built around peaking for the race as he aims to join an elite group of just four riders to have won five Tour titles.