The 21-year-old victim was attacked in Edinburgh's old town, close to the main Hogmanay celebrations sometime between midnight and 2.30am on new year's day.
The incident took place in the Canongate area, and police are keen to speak to anyone in the area at that time.
The suspect is described as white, late teens or early 20s, medium to heavy build with dark spiky hair and a noticeable gap between his front teeth.
Detective Inspector Alyson Brown, who is leading the investigation said: "The Canongate would have been busy with members of the public out celebrating Hogmanay and we are particularly interested in speaking to revellers or locals who were in the area after midnight and remember seeing or hearing anything suspicious.
"I would urge anyone who recognises the description of the suspect to come forward immediately.
"Officers continue to provide a high-visibility presence within the Canongate to conduct further enquiry, engage with the public and offer reassurance to the public.
"Anyone with information relevant to this investigation can speak with these officers, contact Police Scotland on 101 or make a report via the charity Crimestoppers on 0800 555 111."