It happened just before 9 A.M., eight miles north of LaPine.
Oregon State Polcie say a pickup driven by an adult male was northbound on Highway 97 when it crossed the center line and collided nearly head-on with a southbound commercial truck.
The pickup driver was taken to St. Charles in Bend with serious injuries. The semi driver was not injured.
Southbound traffic was detoured onto Vandevert Road, while northbound traffic was diverted onto State Rec Road.
The highway is expected to be closed until around noon.