Police are concerned for the welfare of teenager Rebecca Lyons who has been missing since October 27.
The 15-year-old girl, who has been living at a care home in Hassocks was last seen in Widdicombe Way, Brighton, on October 31.
She has links to Brighton but police are concerned due to her age and vulnerability.
She is described as white, 5ft 3in, with red collar length hair, green eyes and speaks with a southern accent.
She was wearing black leggings, a blue t-shirt, a green jacket with multi-coloured stripes on the shoulder area and blue and black Adidas trainers.
Anyone who knows her whereabouts is asked to call police on 101 quoting serial 857 of 27/10.