Thames Valley Police is appealing for help in locating a missing girl from Bicester, which is half an hour away from Milton Keynes.
Rehem Khimir, also known as Ray, aged 15, was last seen in Banbury Road, Bicester on Wednesday (12/8) evening.
Rehem was last seen wearing a grey top, green shorts and white and black striped trainers. She also has a gold nose stud.
She is known to frequent Swindon, Oxford, Slough, Reading and Yorkshire.
A police spokesperson said: "Officers are appealing for help in locating Rehem as we are becoming increasingly concerned for her welfare.
"If you think you have seen her, or may know where she is, please get in touch with police by calling 101 and quoting reference 43200249604.
"Rehem, if you see this please get in touch with the police or your family, we just want to know you are safe."