All other passengers in both cars were uninjured.
The crash occurred on Malaghans Rd, between Dalefield Rd and Coronet View Rd.
Both cars were travelling from Queenstown towards Arrowtown.
The first car, a green Holden Berlina sedan, was being driven by a Queenstown woman in her 20s, with three male passengers also believed to be local and in their 20s.
According to Constable Phill Hamlin, of Queenstown police, the driver was intending to turn right into a driveway on Malaghans Rd, but drove too far, stopped to back up and then turned.
The second car, a 4WD, was coming up behind the sedan and veered towards the right to overtake the stopping vehicle.
The first car, turning right, and the oncoming second car collided, causing a large dent to the middle of the driver's side of the sedan, and minor damage to the front passenger's side of the second car.
The impact of the crash caused the first vehicle to miss the driveway, instead sliding into a ditch beside the road, where the car flipped and landed on the passenger side.
When police arrived at the scene, closely followed by ambulances and fire engines, two of the passengers of the overturned car had already got out of the car.
The female driver appeared to be trapped, and the male passenger in the front seat was also still in the car.
Emergency personnel were able to help them out, and everyone was examined at the scene.
The driver was taken by ambulance to Lakes District Hospital in Frankton, and Const Hamlin said she was later airlifted to Dunedin Hospital to be examined for a possible hip injury.
Const Hamlin did not know yet if charges would be laid. .
