One of the men was left with a double fracture to his jaw after the attack on High Street.
At 11.30pm on Saturday, three men, aged in their 20's and 30's, and were walking on High Street in Banbury, when they approached another group of men by Church Lane at the junction of Butchers Row.
The second group started to abuse and insult the three men and then threatened and assaulted them.
The three victims sought saftey in the Coach and Horses pub, where the offenders tried to enter but door staff refused them entry.
Two of the men required hospital treatment but they have since been discharged. One man received a double fracture to his jaw, the second received bruising and swelling to the face and the third escaped any injury.
It is believed that the offenders were a group of men with at least three of them wearing white t-shirts.
Investigating officer, Detective Constable Grahame Lea of Banbury CID, said: “We are appealing for witnesses following this unprovoked assault that happened on what would have been a busy Saturday night in Banbury.
“We would ask anyone who may have witnessed this assault to please come forward and call 101 quoting reference 43210415051.
“Or if you wish to report anonymously you can do so by contacting the independent Charity Crimestoppers on 0800 555 111.”