Cork city centre is "filthy" and its littered approach roads are "projecting a terrible image for visitors entering the city", according to a new survey on litter.
The latest litter monitoring report by Irish Businesses Against Litter (IBAL) finds that Dublin and Cork city centres have two of the worst litter problems in the country, and have "tarnished" the image of the rest of the country.
But it is particularly critical of Cork, which is to become the European Capital of Culture next year.
In relation to Patrick's Street, the city's principal shopping street, the survey says it "gives the impression of a filthy area, which has deteriorated".
"The litter bins are insufficient for the huge amounts of litter present."
Dublin and Cork city centres, along with Tallaght and Tullamore, are designated as the most littered urban areas in the country, according to the report.
The survey of 30 towns and urban centres finds that there have been major improvements in the cleanliness of many areas, with the number of "litter free" towns and cities doubling to eight.
There has also been a fall in the number of towns designated as a "litter blackspot"' or being "seriously littered" from 14 to four.
Dr Tom Cavanagh, the chairman of the IBAL, which began the surveys three years ago, said the performances of Dublin and Cork had "tarnished what was otherwise an encouraging result". "The study was conducted over the summer period, when tourist numbers are at a peak," he said.
"Despite the efforts of most towns to improve their litter levels, the main gateways to the country remain plagued by litter. Sadly, this is what visitors first encounter on hitting our shores."
An IBAL survey is carried out more than twice a year now by staff from An Taisce using an international system to measure litter level.
In Dublin, the survey finds that Smithfield, which is now a tourist site because of the distillery development, "was very disappointing".
"One litter bin simply isn't enough for the area surveyed. Litter was scattered throughout, on the cobblestones and outside Irish Distillers. Daytime drinking is becoming an issue."
Overall, there has been an improvement in cleanliness levels in three-quarters of the towns and cities surveyed in the report.
Cavan was designated as the cleanest town in the country, followed by Athlone and Monaghan towns. Galway city, which achieved "litter free" status in the report, is the most improved.
In the last survey, carried out in May, it was one of the most littered urban areas in the country.
"Galway has rightly received criticism for its litter levels in the past," Dr Cavanagh said.
"This remarkable performance - in the height of the tourist season - shows how progress can be made in a short spell of time if a local authority gets behind it."