A FEMALE cyclist is in a stable condition with serious head and leg injuries following an incident at Byron Bay last night.

A police media spokeswoman said the 39-year woman was riding along Ewingsdale Rd at about 6.40pm when she came off her bicycle.

The spokeswoman said police are appealing for witnesses to try and determine whether the woman crashed, or was involved in a hit and run.

Paramedics were called to the scene about 300 metres west of McGettigans Lane at 6.40pm.

A NSW Ambulance spokeswoman said the patient was treated at the scene and taken to Tweed Hospital in a stable condition.

The police media spokeswoman said the woman was then transferred to the Gold Coast University hospital.

This is the second serious incident involving a cyclist this year on Ewingsdale Rd, after 66-year-old Michael Pinkerton was killed on February 11 when he was struck by a ute while riding his bike.

Police are appealing to anyone with any information about the incident to call Crime Stoppers on 1800 333 000.