The man was travelling south and died at the scene. He was the only person in the car.
Police said one of the cars may have crossed the centre line. The two women and three children in the other vehicle were taken to Hawkes Bay Hospital, where one woman was in a serious condition last night in the intensive care unit.
A 15-year-old girl was also in a serious condition in intensive care, as was a 9-year-old girl who was serious but stable.
Another girl aged 12 was stable and in a ward while the second woman had been discharged.
In the other accident a 68-year-old Christchurch man died when his car left the road and hit a bank on State Highway 1 south of Greta Valley, near Waipara.
No other vehicles were involved in the crash, which happened just before 1.30am.
Police from Amberley assisted by the serious crash unit are investigating the cause of the crash.
Figures from the Ministry of Transport show that from January this year 160 people have died on the roads. At the same time last year that figure was 233.