The 2004 Fleadh Cheoil, which was held in Clonmel over the weekend, was attended by more than 200,000 people, according to Garda figures.
The festival's organisers had previously suggested that the numbers were as high as 400,000, but gardaí in Clonmel said such figures were "improbable".
Up to 10,000 Irish and international musicians were estimated to have played at the festival.
Although the main competition ran from Friday to Sunday, events were held in the town throughout last week.
The crowds attending the fleadh made accommodation difficult to secure over the weekend.
A spokeswoman for the festival, Ms Maureen McNamara, yesterday told The Irish Times: "Our accommodation office has been working tirelessly to ensure that nobody has been left without a bed. Now with the fleadh running into Mondays, it means that despite the festival finishing many people are staying in Clonmel until Tuesday."
The festival was soured somewhat by an outbreak of violence over the weekend, which led to almost 20 people being arrested.
On Saturday night, 19 people were arrested for public order offences at the fleadh in the south Tipperary town. According to local gardaí, those arrested were mainly from the area.
Those arrested were all charged and released early yesterday morning, and are due to appear before Clonmel District Court next month.
"We must compliment the gardaí for their excellent work throughout the duration of the festival. We are completely disgusted by the events of Saturday night, and it must be stressed that they had nothing to do with visitors of the fleadh.
"Sometimes the locals get over excited, but the gardaí acted quickly," Ms McNamara said.