An appeal has gone out to find Chloe Postlethwaite and Amber Kalliari who are thought to be together.
Sussex police say the teenagers were last seen in Angmering, where they live, at 4pm on Friday, April 13.
Chloe, pictured on the right, is 5ft 5in, of medium build and with dyed blonde hair with brown roots.
The 15-year-old was last seen wearing black Adidas leggings, black trainers and a pink top.
Amber is 4ft 8in, slight, and has very long brown hair. She is also 15 and was last seen wearing a black leather jacket, black top, black leggings and white Nike trainers.
The teenagers have links to Gosport, Brighton, Bournemouth and Tower Hamlets in London.
Anyone with information can report it to Sussex police here or call 101 quoting reference 1258 of 13/04.