Police are appealing for public help to find Cherri Corrigan.
The 15-year-old was last seen at her home address on Windemere Drive in Ferntree Gully about 6.30pm on Sunday 21 April.
Police and family members hold concerns for her welfare as her disappearance is out of character, and have released an image in the hope someone can provide information on her whereabouts.
Cherri is described as 165 centimetres tall with a fair complexion and long straight hair, dyed purple.
She was last seen wearing a black or purple windcheater and carrying a large aqua handbag.
Anyone who sees Cherri or has information on her whereabouts should call Knox Police Station on 9881 7000.