A man has died after a vehicle rolled following a head-on collision on State Highway 1, about 4km south of Putaruru, South Waikato.

Police said two cars crashed head-on about 6pm yesterday and one driver died at the scene. The second driver, also male, received moderate injuries and was taken to hospital.

The Serious Crash Unit is investigating the circumstances surrounding the crash.

"All road deaths are a tragedy and while the investigation is still in the early stages all motorists are reminded to only drive when they are well rested, to avoid distractions and to drive to the conditions," Senior Sergeant Fane Troy said.