Trinity College Dublin has slipped 19 places in the latest world university rankings, but remains the highest-ranked Irish university.
In the UK-based Times Higher Education World University Rankings 2013-14, Trinity College ranked 129, down from 110.
UCD has climbed from 187 to 161 and is the only other Irish university in the top 200.
Universities ranked below 200 are placed in bands.
NUI Galway (301-350) and NUI Maynooth (351-400) have not changed bands, but UCC has risen one band, from 301-350 to the 276-300 bracket.
The compilers of what is regarded as the most prestigious and comprehensive university ranking table said Trinity's decline should be a cause for concern.
However, it added that it is in line with an "alarming" drop in standards across Europe