A 25-year-old man was airlifted in a serious condition after a motorbike crash on Lady Wakehurst Drive, Royal National Park.
The incident occurred around 2.45pm today when two bikes collided.
A NSW Ambulance Service spokeswoman said the man lost a significant amount of blood and fractured his leg.
The Rescue 24 helicopter flew the man to St George Public Hospital, where he remains in a serious but stable condition.
The second motorbike rider, another man in his twenties, hurt his shoulder.
Parts of the road were closed after the incident.