Police are appealing for witnesses and information after a 15-year-old boy was assaulted in Coniston Road, Patchway.
The incident occurred on Thursday 15th September 2011 at around 9pm.
As the victim walked past the green area opposite the Parade Shopping Centre, he was approached by three males.
The first male dressed in a pair of grey jogging bottoms and a dark hooded top shouted something at the victim.
As the victim looked up from his mobile phone, he was punched in the face by the male causing him to fall backwards onto the pavement, hitting his head and knocking him out.
After he came round some minutes later, he found that the leather-effect mobile phone cover that he had in his pocket was missing and the males had disappeared.
As a result of the unprovoked attack the victim was left shocked and dazed with a large black left eye.
Anyone who was in the area at this time and can offer any information regarding the incident is asked to call Avon and Somerset Police on 101 or Crimestoppers on 0800 555 111.