More than 230 people sought help with a gambling addiction last year.
It is a 7% increase on the 217 people who were assessed or treated for gambling as a problem in 2018.
The HSE says the figures come from the National Drug Treatment Reporting System but are not likely to capture all of those who were treated for gambling problems.
Brendan Kelly, professor of psychiatry in Trinity College Dublin, says the figures are the 'tip of the iceberg'.
"Addiction to gambling is far more common than is imagined," he said.
Sinn Féin's health spokesperson, Louise O'Reilly, is calling for a gambling surveillance report to carried out.
"What the Department of Health needs to do is actually take an accurate picture because it's not just an issue around severe gambling addictions, it's actually around problem gambling," she said.
93% of those treated or assessed for gambling problems between 2015 and 2018 were male.