Adur and Worthing Police shared a photo of a 15-year-old, named Lexi, on Tuesday afternoon (April 30).
"We’re concerned for Lexi, 15, who has been missing from Brighton since Saturday,” the statement on social media read.
"She is about 5ft 5in, of slim build, with long mousey brown straight hair. She has brown eyes with big lashes.
“She may be wearing a cropped black Puffa jacket, white and brown flared trousers with a matching top, and white trainers.”
Police said Lexi also has links to Bognor Regis, Peacehaven, Hove, Saltdean, Lewes, Horsham and Worthing.
A spokesperson added: “Please contact us if you see her or know where she could be, quoting serial 1353 of 27/04.”