All 34 of the country's City and County Planning Authorities will come under fire in a new report to be released later this morning.
Each of the Authorities is graded in an academic style under eight criteria, including the percentage of vacant housing stock in a region - with nine scoring Fs, and C being the highest grade achieved.
An Taisce, which carried out this study, says the publication of the Mahon report has seen renewed calls for investigations into the planning matters of local authorities.
Former chairman of An Taisce, Charles Stanley-Smith, said there is no good news in the report.
"The best that we can come up with is three counties scoring a 'C'," he said.
"It's a generally very poor outlook on planning over the past 10 years."