Sussex Police was called to Ditchling Road this morning, after a collision between a pedestrian and a car near The Level this morning (March 24).
Officers said the road was sealed off after the call came in at 7.30am.
A man suffered serious injuries and has been taken to the Royal Sussex County Hospital, police said. They added that the driver was uninjured.
Police said Ditchling Road remains closed for investigation and for vehicle recovery.