Trinity College Dublin has fallen 44 places in the latest Times Higher Education Rankings published this evening.
TCD is down from 120th position worldwide last year to 164th - with the institution itself blaming under-investment for the 'disappointing result'.
The rankings show UCD and UCC remain relatively unchanged in the section between 201 to 250.
NUI Galway though has risen into the group rated between 250 and 300.
Fianna Fáil education spokesperson, Thomas Byrne, suggested a lack of funding is the major reason Irish colleges aren't doing better.
He observed: "The league tables internationally are very important for the reputation of universities.
"The fundamental reason why Irish universities are going down the league tables is because of Government inaction in relation to funding for these universities - and Government disinterest, I would say."
Deputy Byrne added: "What's happening really is we're failing third level students very, very badly."
Trinity, meanwhile, said the decline in the rankings is "part of a pattern which began in the years following the financial crisis when funding per student was drastically cut".
The university's dean of research, Professor Linda Doyle, said: “This is an undoubtedly disappointing result.
"Looking at the scores behind the rank, our performance is steady. However, this is not good enough in a world that sees many of our global competitors improve their scores through focused and sustained investment by their governments.
"There is no denying that continuing underinvestment in university education and research in Ireland is catching up with us.”
Full details of the Irish university rankings are available on the Times Higher Education website.