The Ekka's medium and heavy harness horse classes are set to be axed from the 2020 schedule, with the RNA citing low entry numbers last year as the reason for the change.
Instead the RNA is seeking expressions of interest for Heavy and Medium Harness horse demonstrations, to replace the competition.
In a statement provided to the Queensland Country Life, the RNA said in 2019 just three exhibitors submitted a total of 13 entries across the 14 heavy and medium harness classes.
"This saw 10 of the classes receive one or no entries, prompting the RNA to instead consider public demonstrations for the 2020 Ekka," the statement said.
Trevor and Carolyn Kohler, Mt Tyson, have been entering their horses in the medium and heavy horse classes for more than 12 years.
Mr Kohler said he was very disappointed with the change and didn't believe many former exhibitors would wish to make the switch to a public demonstration.
"There's not enough shows for us to go to any more... the Ekka was our big one and now that won't be there any more," he said.
"We just do it because we love it but now they've taken that away.
"We go to compete because we love it and we love showcasing these magnificent animals to the crowds.
"Over the years the people have come to enjoy the spectacle of the horses and their historical significant role they have played in Queensland's agriculture."
Mr Kohler said exhibitor numbers had dropped due to the ongoing dry conditions but he believed there was still room for the classes to be part of the Royal Queensland Show.
"I know there are people who are building themselves up to come back again when the season is better," he said.
"It costs so much money to keep your horses in show condition when it's so dry and some people can't afford to do that.
"I worry that if they cut the classes from the competition this year that they won't bring them back again."