Police are appealing for witnesses following a serious collision in Bersted.
Officers were called to Chichester Road at around 6.40 am on Tuesday to a report of a woman being hit by a car.
A 77-year-old local woman was airlifted to Royal Sussex County Hospital with serious injuries, and she remains in a critical condition.
The driver of the green Skoda Octavia, a 53-year-old local man, was arrested on suspicion of causing serious injury by dangerous driving. He has since been released on police bail pending further enquiries.