Police and emergency services were called to London Road, Balcombe, today (Saturday 6 July) following a collision between a cyclist and a car.
Officers arrived at the scene of the collision near the Cowdray Arms pub at around 3pm.
The cyclist, a man, thought to be in his 20s has been taken by ambulance to St Georges Hospital in London with serious head injuries.
The road remains closed both ways while rescue, recovery and collision investigation work is underway and drivers are advised to use an alternative route.
If you witnessed the collision and have not yet spoken to officers please call 101 quoting serial 929 of 6/7 or email firstname.lastname@example.org