A worried father has issued a direct appeal urging his missing son to return home.
Rhodri Owen, 17, was last seen leaving his house in Morganstown, Cardiff, at around 1700 BST on Friday.
Police say his disappearance is "completely out of character".
His father Richard asked his son to come home, saying it would be "wonderful" to see him.
He said: "Rhodri it would be wonderful to have you back for up and coming birthdays this week.
"No-one is cross or angry with you.
"You have a great future ahead of you and a holiday to look forward to.
"You have the most supportive friends, who have been fantastic."
When Rhodri was last seen, he was wearing a red polo short with a Lyle and Scott Motif, trousers and white trainers.
Det Sgt Andy Miles, from Fairwater CID, said: "We are becoming increasingly concerned for Rhodri who has been missing since Friday and would appeal for anyone with information to contact us.
"His disappearance is completely out of character and as you would expect his family and friends are desperate to have him home safe and well.
"We are in close contact with Rhodri's family who are being kept fully updated."
Since Rhodri was reported missing, police have been carrying out extensive enquiries with search teams in and around the Morganstown area.
They are also checking CCTV for any possible sightings.
"I would urge anyone with information on Rhodri, not matter how insignificant it seems, to contact us," added Det Sgt Miles.
If you can help please contact South Wales Police on 101, Fairwater Police Station direct on 02920 571516 or Crimestoppers anonymously on 0800 555 111.