UPDATE: Bree has been located safe and well.
Mandurah Police are urgently seeking information from the public to help locate Bree Ann Newsome.
The 15-year-old is believed to be wearing black leggings and a light coloured t-shirt.
There are serious concerns held for her welfare as she is without vital medication.
Anyone with information on her whereabouts or who may see Bree is asked to contact police immediately on 131 444.