Gardaí in Dublin are seeking the public's assistance in tracing the whereabouts of 17-year-old Mark O' Brien is missing from his home in Cherry Orchard - in Ballyfermot.
Mark was last seen in the Talbot St. area of Dublin city centre last Saturday.
He is 5ft 4 tall, and weighs approximately seven stone.
He 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 is asked to contact Ballyfermot Garda Station.