Research published by the Rape Crisis Network Ireland has found that only one in three rape cases are prosecuted by the Director of Public Prosecutions.
The main reason given for the low rate of prosecutions is a lack of evidence.
The study has also found that rape convictions are more likely when rape fits a narrow stereotype, such as when someone is raped by a stranger in a public place.
However, the most common rape is committed in a private place by a person known to the victim.
Alcohol was found to play a role in rape, with three in four suspects consuming alcohol on the day of the offence.
The Director of Public Prosecutions James Hamilton said the whole system of jury selection needs urgent reform.
Speaking at the launch of the RCNI research, Mr Hamilton said juries in their current form are not representative of society as a whole as so few middle class people end up on juries.
Mr Hamilton said he believes this caused a major problem for all cases, not just rape cases.
He said wanted to see the whole process reformed and brought into the 'modern era of information technology'.
Consecutive sentences unrealistic for rape - Carney
Meanwhile, the presiding judge of the Central Criminal Court has said that it is sometimes unrealistic to award consecutive sentences at rape trials.
Mr Justice Paul Carney said many rape cases, including ones with familial abuse over a long period of time, often involved 100 counts of rape and sexual assault.
He said he did not believe anyone would be in favour of 'American-style sentences of hundreds of years' being imposed.
He was responding to criticisms made by the RCNI that there was an 'apparent judicial hostility to consecutive sentences'.
Mr Justice Carney also said he would not be in favour of a gender quota being introduced with regard to rape trial juries.
He said he believed that women were often the harshest critics of female rape victims, especially when it came to the issues of drink, or going to strangers' flats or into their cars.
He said he believed introducing a gender quota on rape trial juries, to include more women, would increase acquittals.
