A crash involving a motorcycle and scooter closed Poverest Road in Orpington this morning.
The incident happened just before 8am at the junction with Marion Crescent.
A man in his 20s was airlifted to hospital with a serious head injury.
Police closed Poverest Road from Marion Crescent to Cray Avenue, but it has since re-opened.
A London Ambulance Service spokesman said: "We were called at around 7.55am this morning to reports of a road traffic collision involving a motorbike.
"We sent a single responder by car, an ambulance crew and London's air ambulance to the scene.
"We treated a man, reported to be in his 20s for a head injury.
"He was taken as a priority to the Royal London Hospital."