Kent Police was called at 2.55am on Wednesday 4 July regarding a report that a car had struck a tree on the A20 Ashford Road near Sellinge.
Officers, South East Coast Ambulance Service and Kent Fire and Rescue Service attended the scene where a man was treated for serious injuries. He was taken to a London hospital by air ambulance for further medical attention.
The road was closed while emergency services dealt with the incident.
One lane was reopened at around 5.47am and there is likely to be some traffic congestion while Highways teams complete repairs at the scene.