A Rockdale man, 33, was killed when his bike crashed into the back of another vehicle on the Illawarra Highway at about 4.30pm.

Police said a Ford Falcon utility had stopped and was waiting to turn right about 2km east of Jamberoo Mountain Road when the motorcycle crashed into the back of it, causing the rider to be thrown from his bike.

The driver of the ute, a 21-year-old Robertson woman, and her 21-year-old passenger were not injured.

Police urged anyone who saw the crash to contact Crime Stoppers on 1800 333 000.

A report will be prepared for the coroner.

The accident brought the state's road toll to 410, which is up 94 on a year ago.