Fire crews from Chichester and Midhurst were called to Folly Lane in the village this afternoon.
They remained at the scene at 3.25pm.
Motorists have been advised to avoid the area where possible.
A West Sussex Fire and Rescue Service spokesperson said on social media: "Crews from @ChichesterFire and @43Midhurst are dealing with a road traffic collision at Folly Lane, #Barlavington where a car is in a ditch.
"Please avoid the areas if possible and allow extra time for journeys."