One lane of the New England Highway near Uralla has been reopened under stop/slow traffic control.
The highway was initially closed in both directions after a single vehicle crash earlier today.
Motorists are advised to allow extra travel time and follow the direction of crews on site.
The Westpac Rescue Helicopter has been called to a single vehicle rollover on the New England Highway.
The crash - which has closed the highway in both directions - occurred south of the Kentucky turnoff, approximately 17 kilometres south of Uralla.
The driver of the car, a young female, has been taken to the Armidale Hospital by road ambulance with minor injuries.
He was treated and stabilised at the scene by the helicopter medical crew and road ambulance paramedics.
He has sustained possible pelvic injuries and multiple lacerations in the accident and is being transported to the Tamworth Rural Referral Hospital in a serious condition.
Motorists are advised to avoid the area of the highway.
Motorists who need to travel through the area can use the Oxley Highway and Thunderbolts Way via Walcha instead, and should allow plenty of extra travel time.
Emergency services and traffic crews are on site, and police crash investigators are also on their way.