Police are appealing for witnesses and information after a collision involving a car and a motorcycle on the A259 at Hooe.
The incident happened shortly before 8.30am on Wednesday, November 29.
A motorcycle rider was taken to the Royal Sussex County Hospital in Brighton with serious injuries, where he remains in a serious but stable condition.
The driver of the car was not injured.
Road closures were put in place in both directions between Little Common and Pevensey, and motorists are advised to find alternative routes.
Officers are appealing for witnesses or anyone with relevant information, such as dashcam footage, to report it to Sussex Police by emailing: [email protected] and quote Operation Murray.