Great Eastern Highway was closed in the Wheatbelt after a road train rolled in the early hours of this morning.
The road train rolled just before 1am, blocking both lanes of the highway near the Bruce Rock-Doodlakine Road, 10km east of Kellerberrin.
The driver was airlifted to Royal Perth Hospital by the RAC rescue helicopter.
A police spokesman said the westbound lane of Great Eastern Highway was re-opened just after 7am.
Towing contractors were loading the road train onto semi-trailers.
Motorists are advised to expect delays.