The Economic and Social Research Institute (ESRI) is warning of the pitfalls of re-introducing third-level fees.
The warning follows confirmation from Education Minister Batt O'Keefe that he plans to bring back tuition fees in the coming years.
Mr O'Keeffe says existing students will not be affected, but anyone going to college from this September can expect to be paying fees from 2010 onwards.
In a report out today, the ESRI says that, while more than 60% of Leaving Cert pupils go on to third-level education, most are from better-off backgrounds.
However, it says there is a danger that re-introducing fees could make this even worse and any proposals on the matter need to be well-considered and accompanied by measures to help vulnerable groups.