A child has been injured after falling from a motorbike at Heaton Lookout in the Watagan Mountains.
A NSW Ambulance spokesperson said "a young boy had an accident on a motorbike" at about 10.30am.
"He suffered serious head injuries," the spokesperson said.
"We winched down our critical-care doctor."
The incident happened in the suburb of Olney, near a picnic area in the Heaton State Forest.
A Westpac Rescue Helicopter spokesperson said NSW Ambulance paramedics and a NSW Health doctor from the helicopter's critical-care medical team were "winched into the isolated location".
The child was treated and stabilised "before being transported by road, accompanied by the medical team, to John Hunter Hospital".
The area, which is west of Toronto, is a popular area for dirt bikes and four-wheel-drives.