Gardaí in Ballyfermot have appealed for assistance tracing 17-year-old Mark O'Brien, who has been missing from his home in Cherry Orchard, Dublin, since last Friday.
Mark was last seen in the Talbot Street area of Dublin on Saturday.
He is 1.63m (5'4") tall, weighs about 44.5kg (7st) and has black hair and brown eyes.
When last seen Mark was wearing navy tracksuit bottoms, a navy and grey jacket and navy running shoes.
Anyone with information on his whereabouts is asked to contact Ballyfermot Garda Station on 01-6667200, the Garda Confidential Line 1-800-666-111 or any garda station.