The drivers of two cars were killed after one is believed to have drifted across the centre line and collided with the second vehicle head-on last night.
The deaths were among three road fatalities at the weekend.
A passenger from one vehicle, a 51-year-old woman, remains in a serious condition in hospital.
She was airlifted to Palmerston North after the crash on State Highway 1 at Manakau, south of Levin, about 10.40pm.
The male drivers of two cars, believed to be aged 26 and 55, were from Palmerston North and Levin respectively. The injured woman was a passenger in the car travelling north.