A Melbourne teenager has been missing for almost three weeks and police are appealing for help to find her.

Courtney McKendry, 15, disappeared from her home in Oakleigh East in the city's south-east on June 26.

Courtney McKendry.

Police believe the teenager could still be in the outer eastern suburbs and concerns are held for her safety due to her age.

Courtney is 165cm tall with a thin build and brown/auburn hair.

Police released a photo of her in the hope someone may know where she is.

Anyone with information should phone Crime Stoppers on 1800 333 000.