Police say a white Toyota utility was being driven with two passengers in the tray of the vehicle on Acton Road, towards Cambridge.
As the vehicle negotiated the round-about at the intersection of Alliance Drive and Acton Road, a male passenger fell from the tray of the utility onto the roadway.
The injured passenger was then taken in the utility to a private residence at Oakdowns.
Anyone who may have witnessed the incident or the vehicle being driven on Acton Road or South Arm Road are asked to contact Constable Hayden Williams at the Bellerive Police Station on 6230 2859 or Crime Stoppers on 1800 333 000.
