A video has been posted on social media showing an altercation in a Balmoral Show bar tent, triggering an investigation by show organisers and police enquiries.
The video, which has been viewed over 100,000 times on Facebook, shows security staff trying to break up the fight which involved around a dozen people.
There were no reports of anyone suffering serious injuries, according to Royal Ulster Agricultural Society (RAUS).
The organisers of Northern Ireland's largest agricultural show are now investigating the incident.
The Police Service of Northern Ireland (PSNI) are also making enquiries.
A RUAS spokeswoman said: “There was an altercation at the bar area, which was quickly brought under control by the event security personnel and we believe no one was seriously injured.
“It is sad that a few people resorted to this behaviour when tens of thousands of people enjoyed a fun family day out.
“The society will be fully investigating this matter and appropriate action taken.”
This year’s Balmoral Show ran from 15th to 18th May at Balmoral Park, Lisburn. A record number of people attended, over 120,000 visitors throughout the four days.