A 24-year-old man needed 30 stitches in his head after being attacked in a Belper pub.
He was knocked to the ground and then kicked during the assault in the toilets of the Nag’s Head, off Market Place.
The attack happened shortly after midnight on Saturday, November 19.
The victim was taken to Royal Derby Hospital for treatment.
Many of the stitches he needed had to be inserted around one of his eyes. Some were put inside an eyelid.
A police spokesman said: “The man is believed to have been attacked by two men who were in the pub.
“We are keen to trace other drinkers, including a man who is thought to have tried to help the attacker and alerted pub staff.”
Officers are also interested in hearing from anyone who may have heard someone bragging about the attack.
The victim was allowed to return home from hospital the following day, but he will have to go back in for more treatment in the future.
Any witnesses, or anyone who has any information about the attack, is asked to call Derbyshire Police on the force’s new non-emergency number, 101.
Alternatively, ring the Crimestoppers hotline, anonymously, on 0800 555 111.