Ireland has slipped one place from 17th to 18th in a new global report into corruption perceptions in 168 countries.
Transparency International's Corruption Perceptions Index found Ireland is perceived to be far less "clean" than many of the world's advanced democracies.
The findings, however, show a slight improvement in Ireland's score from 74 to 75 out of 100. Japan and Hong Kong share 18th place in the global ranking.
Denmark came first for the second year in a row, with North Korea and Somalia the worst performers.
Britain was in joint 10th place along with Germany and Luxembourg.
The big decliners in the past four years include Libya, Australia, Brazil, Spain and Turkey. The big improvers include Greece, Senegal and the UK.
TI Ireland Chief Executive John Devitt said: "Some important reforms, such as new whistleblower protections and lobbying regulations have recently been introduced and will help prevent wrongdoing.
"However, the failure to publish new anti-corruption legislation, four years after it was announced, is hugely disappointing and should be a source of embarrassment for the Government."
Mr Devitt acknowledged that new political finance rules and reforms enacted in 2012 have "an important role to play in helping prevent corruption" but said the investigation of corruption has suffered as a result of depleting resources in the gardaí and Standards in Public Office Commission.
TI Ireland has also been critical of delays on a decision by the director for public prosecutions on whether court action will follow garda investigations that were undertaken as a result of the final Moriarty Tribunal report.