A 35-year-old Tirau man is in a serious condition after a crash north of Tokoroa on Sunday night.
Police say the man failed to take a bend on State Highway One, rolling his Toyota Hilux 4WD at around 11:30pm.
The man, who was the sole-occupant of the car, was thrown from the vehicle.
Alcohol is not believed to be a factor.
However police say the fact that the driver was thrown from the vehicle indicates that he was not wearing his seatbelt.
The Baytrust rescue helicopter flew the man to Waikato Hospital where his condition was described as critical.