Police investigating the death of a Christchurch woman are appealing for witnesses to her falling from a car late last month.

Nicole Morris, 30, fell onto the road on Bealey Ave on January 27 and died in hospital on Sunday.

Police are treating her death as unexplained and are investigating on behalf of the coroner.

Ms Morris had been in a silver Ford Mondeo.

"She was seen falling onto the road between the intersections of Manchester Street and Bishop Street," said Detective Senior Sergeant Greg Cottam.

"A motorist behind the vehicle she fell from stopped to help," he said.

"We are appealing for witnesses who saw Ms Morris fall from the car to come forward, particularly anyone who saw the vehicle she was in."