Police are appealing for witnesses after they were told at least 15 people were involved in a brawl during the Yass Rodeo at Yass Showground last month.
Police said the brawl happened between 3pm and 5pm on Saturday November 8, leaving a man seriously injured with a broken jaw.
The Hume Crime Manager, Detective Inspector Chad Gilles, said the fight "tarnished this community event" and police were appalled by the violence.
"Police are not only appealing for witnesses, but anyone who recorded the altercation, to come forward," Detective Inspector Gilles said.
"Police are keen to speak with anyone who witnessed the fight and are especially keen to view any footage to help catch those responsible and put them before the courts."