The man, believed to be in his mid to late 20s, became trapped when the Nissan Skyline in which he was a passenger and an oncoming Toyota Surf collided at a bend in Works Rd.
Sergeant Tony Woodbridge, of Oamaru, said the drivers of the vehicles, a woman from Christchurch and a man from Oamaru, suffered "minor scratches" in the crash.
He said the victim was cut free from the vehicle in about 10 to 15 minutes by members of the Oamaru Volunteer Fire Brigade, and he had been lucid, speaking to members of St John Oamaru who attended the incident.
A police investigation is under way.