The RAC Rescue has been sent to a car crash on Injidup Spring Road, near the intersection of Karli Rise, in Yallingup.
A St John Ambulance spokesperson said a woman in her 20's rolled her car when it hit a tree.
The woman was taken to Bunbury and transported by road to Bunbury Regional Hospital.
The RAC Rescue helicopter was expected to land at the hospital around 3.40pm.
Volunteer Fire and Rescue Service firefighters are assisted at the scene.
The RAC Rescue helicopters are sponsored by RAC, funded by the State Government and managed by the Department of Fire and Emergency Services (DFES).