Just 11% of sexual crimes reported to gardaí in 2018 have resulted in someone being sanctioned.
The Central Statistics Office has published new figures which show that sex offences have the lowest detection rates compared to any other crime.
Gardaí solved three quarters of murders committed last year, the figures show.
Detection rates for crimes reported in 2018 vary, depending on the type of crime.
A crime is considered 'detected' when a suspect has been identified and proceedings have commenced.
Drug offences had the highest detection rates last year, at 85%, while public order offences had a detection rate of 81%.
CSO Statistician Sam Scriven outlined the rates for other serious crimes.
Mr Scriven said: "The rate for murder and manslaughter is 72%, but at the lower end of the scale, the detection rate for burglaries was 16% and 11% for sexual offences."
This is the first time the CSO has published crime data since suspending the practice two years ago over concerns it had with the quality of data coming from Gardaí.
The data collection system has since been restructured, which Deputy Commissioner John Twomey hopes will give victims confidence in the Gardaí.
The Deputy Commissioner said: "We want to help you in whatever way we can and we are making changes to our practices and processes to give you the confidence in that regard."
The report also found that recorded crime rates per head of population were higher in Dublin than anywhere else in the country.
It showed that the rate of robberies, hijackings and thefts are higher in the capital per head of population compared to anywhere else in Ireland.
