Sutton police are searching for 15-year-old Alfie Harry, who went missing from his grandparent's home in Dorking over a month ago.
Alfie is believed to be staying with friends in Sutton, mainly in St Helier or the Papermill Close area of Carshalton.
Family members have had irregular contact with the teenager since he went missing, but there has been no contact or sightings over the last few days.
Police say he has no money or means to support himself, and needs medication for an ongoing condition.
PC Richard Owen of Sutton’s Missing Persons Unit, said: "We need to find Alfie as soon as possible.
"If you know where he is, please get in touch."
He first went missing on Tuesday, July 8.
If you see Alfie call Sutton police on 101 quoting ref no: 14MIS024256.
Any information can also be passed anonymously to the Missing People charity on 116000.