It happened around 8:15, on Highway 81, between Waurika and Ryan.
The Oklahoma Highway Patrol says 24- year old Frankie Foster was driving a Jeep, south on 81, when for some reason, it crossed the center line.
Troopers say the Jeep slammed into a trailer, loaded with 70- head of cattle, driven by 61- year old Clarence Myers, of Iowa Park.
Foster was wearing a seat belt, and the air bag also deployed.
She was still ejected, though, and was pronounced dead at the scene from massive head injuries.
Owens and Brumley in Burkburnett is handling Foster's services, and arrangements are expected to be made tomorrow.
Troopers say Myers was not injured.