A female cyclist has been rushed to hospital with head injuries after she was struck by a car in peak hour traffic at a busy city intersection.

Emergency responders raced to the scene after reports of a collision at the corner of Margaret and Kent streets, in Sydney's CBD shortly before 5pm on Thursday.

Police blocked the area to protect the injured woman lying on the road.

The collision occurred in front of dozens of shocked onlookers, who rushed to the cyclist's aid and assisted her until paramedics arrived. 

The woman's orange bike lying on the road next to her appeared to be intact.

The area has bike lanes in both streets located near where the woman was hit. 

A NSW Ambulance spokesman told Daily Mail Australia three crews attended the scene. 

'Paramedics treated a woman in her 30s for a head injury,' he said.

The cyclist was transported to St Vincent's Hospital where she is in a stable condition.

Daily Mail Australia contacted NSW Police for comment.