A 50-year-old woman was taken to Leeds General Infirmary by air ambulance after a crash outside Tadcaster.
North Yorkshire Police were called at 9am on Friday (January 27) after a green Rover 25 had left the A162 just south of Towton and landed in a ditch.
The woman was a passenger in the vehicle. Although the extent of her injuries was not known they were believed to be serious.
The driver of the car, a 41-year-old woman suffered minor injuries in the incident.
The A162 in Barkston Ash was closed in both directions causing severe disruption.
Any witnesses to the collision are urged to contact North Yorkshire Police on 101.