A male cyclist suffered a head injury after he was hit by a car in Albion Park Rail about 11am.
The 83-year-old was cycling south on the Princes Highway when his bicycle veered across the south-bound car lanes and collided with a passing vehicle, Lake Illawarra police said.
Ambulance officers and Lake Illawarra police attended the scene.
The man was treated at the scene by paramedics before being airlifted to St George Hospital in a serious but stable condition.
The Princes Highway has been reopened.
Police are conducting inquiries into the incident.