A motorcyclist from Brighton has died after a crash involving a Peugeot car.
The man, from Saltdean, died at the scene on the A2037, close to the corner of Horn Lane, in Small Dole, near Upper Beeding.
The driver of the car, a woman from Small Dole, suffered serious injuries and was taken to Worthing Hospital.
The crash happened at about midday.
The Highways Agency said that the road was closed in both directions.
The agency said: “The main road between Upper Beeding and Henfield remains closed both ways for clean up and investigation work.
“The sensors are not reporting any major queues approaching the closures.”
Anyone who saw the crash or either vehicle shortly before is asked to phone Sussex Police on 101.