It happened on the Killead Road in Crumlin on Friday, February 26.
The PSNI say officers received a report around 5pm that a blue Peugeot 307 car had left the road and struck a tree.
The driver, a 17 year old male, was taken to hospital where he remains in a critical condition.
The road is closed at this time as enquiries continue.
Inspector Colin Ash has appealed for anyone who saw the car being driven in the area or who has any information about the collision to contact police in Antrim on 101.