Man found unconscious on Qld road

Police are unsure how a man found unconscious in the middle of Gold Coast hinterland road suffered serious head injuries.

"This could be a hit and run or it might be an assault, we are currently conducting inquiries in an attempt to understand what occurred," Detective Inspector Marc Hogan said.

A passing motorist spotted the man, believed to be aged in his 30s, lying on Tallai Road about 5.30am on Tuesday morning.

He was taken to Gold Coast University Hospital in a serious condition, with investigators establishing a crime scene.

It took several hours to identify him, as he wasn't carrying any form of identification.

Police are urging anyone with information to come forward.