The accident occurred at 11.30am when a motorcycle with a side car, ridden by the woman, was travelling east along the Illawarra Highway. It collided with a west-bound motorcycle just past the Robertson Pie Shop heading towards Macquarie Pass.

The woman died at the scene. No-one had been in the sidecar.

A male rider of the other bike was airlifted to Liverpool Hospital in a serious condition.

He was reported to be in a critical condition last night.

A crime scene was established and inquiries into the cause of the crash were continuing.

The highway had to be closed between Jamberoo Mountain Rd and the Tourist Rd for five hours.

A report into the collision will be prepared for the information of the NSW Coroner.