Noah Donohoe (14) has been missing since Sunday.
He was last seen in the Shore Road area of North Belfast.
The PSNI believe that the teenager may have sustained a head injury after falling from his bike.
This assumption comes from an eyewitness who stated that they saw someone, matching the description of Noah, fall off their bike in North Queen street which may have lead to the individual “possibly sustaining a head injury”.
It is believed that Noah got back up on his bike and travelled to the Northwood Road.