Police have released images of three men they want to trace over a late night assault on Waverley Bridge which left the victim with a fractured skull.
The 25-year-old victim was rushed to hospital following what officers say was an unprovoked attack at about 3.30am on Sunday, July 23.
Detectives released the images yesterday saying they were keen to trace the males pictured who were in the area at the time of the attack.
Anyone who recognises them is being urged to contact police immediately.
Detective Constable Graham McIlwraith, who is leading the inquiry, said: “The victim suffered a serious head injury as a result of this incident and police have been conducting various inquiries including viewing several hours of CCTV footage from in and around Edinburgh City Centre.
“The males pictured are believed to be of significance to our investigation and anyone who can assist in tracing them is asked to come forward.
“Similarly, we would ask these males to get in touch with police and help with our investigation.”
The victim had been walking on Waverley Bridge towards Market Street, near to Waverley Station, with two friends at the time of the attack.
They were said to have been approached by a man who assaulted the 25-year-old.
The male suspect then left the scene with friends in an unknown direction.
The victim suffered severe head and facial injuries and was taken in a serious condition to the Royal Infirmary of Edinburgh for treatment.
The suspect is described as a white man in his mid-twenties. He has an average build with short dark wavy hair and was believed to be wearing a beige or brown T-shirt.
He was also in the company if three-four other men, all in their mid-twenties, with one wearing a blue T-shirt. All of the men are said to have witnessed the incident.
DC McILwraith said: “This was a violent and frightening attack for the victim and we are eager to trace the man responsible as soon as possible.
“I would ask anyone who was in the Waverley Bridge area in the early hours of Sunday morning, and saw either the incident, or the man and his companions in the vicinity, to please get in touch with us immediately.”
Anyone with information can contact officers at Gayfield CID on 101, quoting incident number 0973 of July 23, or the charity Crimestoppers in complete anonymity on 0800 555 111.