Sergeant Blair Corlet, of Oamaru, said police recorded the woman driving at 129kmh on State Highway 1 north of Hampden and attempted to stop the driver of the 1992 Toyota Sprinter.
A police officer activated his police car's lights and sirens but the woman, travelling north, failed to stop and led police on a pursuit reaching speeds of up to 140kmh, he said.
Just south of Herbert, about 10km away, the driver lost control of her car, which slid across the road.
It crashed through a wire fence and rolled ''multiple times'' before coming to rest under trees about 30m down a hill in a paddock.
Emergency services were sent to the scene and a rescue helicopter arrived just after 5pm to fly the woman to Dunedin.
The driver was the only occupant of the car.
The road was not blocked, but fire crews controlled traffic at the scene.
Police inquiries were ongoing, Sgt Corlet said.
A police statement said the Serious Crash Unit had been notified, and the Independent Police Conduct Authority would also be advised.
Anyone who saw the crash or the driver, and who had not already spoken to police, was asked to contact Oamaru police on (03) 433-1400.
