Almost 3,000 criminal cases were not brought before the courts last year because of insufficient evidence.
The figure is contained in the annual report of the Director of Public Prosecutions for 2007.
The office of the Director of Public Prosecutions received just over 15,500 files from the gardaí in 2007 - an increase of just over 2% on the previous year.
The figures show that almost 10,000 cases were disposed of, but in almost 3,500 of these, a decision was taken not to go ahead with a prosecution.
In the vast majority of cases, the reason for the decision was insufficient evidence.
The courts heard 39 applications by the DPP last year for reviews of sentences he considered unduly lenient. 30 of these were successful.
The report also shows most convictions for offences coming before the circuit and central criminal courts are secured after a guilty plea from the accused rather than a verdict from a jury.
In his foreword to the report, Director James Hamilton says the fact that his office is physically divided over a number of buildings means it cannot operate with optimum efficiency.
He also says he should be in a position in the very near future to come to a final conclusion as to whether a way can be found to give victims or their families reasons for his decisions.