Dramatic vision of a road rage altercation shows a man being thrown off the bonnet of a car on a busy road in Adelaide.

Police said they were investigating the incident, which happened at suburban Dulwich during morning peak-hour traffic on Wednesday.

Part of the incident was filmed from the window of offices nearby and posted to Facebook.

Police said there was an altercation between two drivers at the corner of Fullarton and Greenhill roads and one man climbed onto the bonnet and windscreen of the other car.

The driver of that car then took off, flinging the man onto the road.

Ambulance paramedics later took him to the Royal Adelaide Hospital for treatment of a minor head injury.

Police said both drivers had reported the matter to them and they were investigating the circumstances.

They urged anyone who saw the incident to contact Crime Stoppers on 1800 333 000 or online.