You won't believe what Vin Diesel's biggest fear is!

Vin Diesel has revealed he has a fear of riding roller coasters.

Which is pretty surprising considering he is best known for his willingness to perform dangerous stunts in films like The Fast and the Furious series and the xXx franchise.

During an appearance on The Tonight Show Starring Jimmy Fallon the action star opened up about his fear.

"I'm not a real roller coaster kind of guy," he said during the show, which was held at Universal Studios Florida in Orlando to celebrate the opening of Fallon's new ride, Race Through New York.

In fact, the 49-year-old stated that he would rather try just about any stunt imaginable than be forced to whizz around on an amusement ride at a theme park.

"I do stunts for a living, (but) I just don't do roller coasters," he admitted. "I would rather ride a GSX-R (motorbike) with a loose screw, maybe 170 miles an hour down the turnpike without a helmet, than get on a roller coaster."