Police are appealing for witnesses and dashcam footage following a collision involving a motorcycle and a car near Herstmonceux.
Emergency services were called to the A271 Hailsham Road between the junctions with Old Road and Under Road at about 8.20pm on Monday, April 18.
A collision was reported involving the rider of a motorcycle and a blue Volkswagen. The 48-year-old rider suffered serious injuries and was taken to the Royal Sussex County Hospital where he remains.
Officers thanked the public for their patience while road closures were in place.
Anyone who witnessed the collision or anyone with relevant footage of the vehicles in the area is asked to contact Sussex Police online or call 101 and quote Operation Jackdaw.