UCD earned €1.8million in exam resit fees in just one academic year.
Figures obtained by the Sunday Independent show that the university charge €230 for students to repeat a module or to resit an exam.
The charges are implemented when a student fails to make the grade the first time around and each university imposes its own fees.
Trinity College doesn't charge students to resit exams but records from UCD show the university charged €1,853,455 in exam repeat and resit fees for the academic year 2014/2015.
The University of Limerick made €352,033 in fees for repeat exams and charge €171 to resit a module while University College Cork made €211,925 in resit fees and charges €35 per module.