The incident happened around at 2130 hrs on Sunday 29th April at the Whispers Lounge Bar on Tranent High Street.
A 39-year-old man entered the pub and soon after became involved in a disturbance with another male customer.
During this time, he was assaulted and suffered a serious injury to his right ear, a black eye and scratches to his face.
The victim was taken to the ERI where he continues to be treated.
Officers are now urging anyone who can assist with their enquiries to come forward.
Apolice spokesman said: “During the struggle, the victim has had the top of his right-ear bitten off and will be left with permanent disfigurement.
“We are keen to trace the suspect responsible for this attack and would urge any patrons who were within the Whispers Lounge last night and who witnessed the assault to contact police immediately.
“Similarly, anyone with any other information that can help with our investigation is also asked to get in touch.”
Anyone with any information can contact Lothian and Borders Police on 0131 311 3131, or the charity Crimestoppers in confidence and complete anonymity on 0800 555 111.