The Rape Crisis Network has expressed "deep concern" at the 47 per cent drop in unlawful carnal knowledge cases reported to gardaí between April and June this year, compared with the same period last year.
Fiona Neary, director of the Rape Crisis Network, said this fall in reported cases may be as a result of a loss of confidence in the legal system following the Mr A case.
"We know that someone who has been raped will be very sensitive to the possibility of any re-victimisation in going through the courts," she said.
"Seeing a convicted sex offender walk free without completing his sentence, and seeing the ensuing chaos and crisis-driven reaction by our Government, does nothing to build any confidence that our legal system will deliver justice."
The Dublin Rape Crisis Centre pointed out that it had recorded a 29 per cent increase in the number of call-outs to the sexual assault treatment unit in the Rotunda Hospital in the first three months of this year, compared with the same period last year.
Ellen O'Malley-Dunlop, chief executive of the centre, said the number of "recent rape first calls" to its telephone service was also up by 29 per cent from 2005.
She said the drop in reported sexual crimes unfortunately did not represent a fall in actual crime. According to the Sexual Abuse and Violence in Ireland report, only three in 1,000 victims of rape and sexual assault report these crimes.