A cyclist has been struck and killed by a car being driven by an elderly woman in Sydney's south-east.

The 35-year-old was riding alongside her husband shortly after 10.30am on Sunday morning when they were struck by a hatchback in Pagewood.

Paramedics treated both but the woman died at the scene, while her husband escaped with relatively minor injures.

He is being treated in hospital.

The elderly woman behind the wheel of the hatchback has been taken to hospital for mandatory blood and urine tests.