Between 60 and 80 per cent of students in some third-level computing and engineering courses are dropping out, new data shows.
Young men with low Leaving Cert points are at a particularly high risk of failing to complete their college courses.
The findings are contained in a study by the Higher Education Authority (HEA) which tracked the progress of thousands of students who started third-level courses over a 10-year period.
Despite concerns over high drop-out rates in some areas, the study's authors say Ireland compares well internationally overall.
Overall, three out of four undergraduates who entered higher education between 2008/09 and and 2010/11 completed their courses and graduated.
Completion rates were highest in teacher-training colleges, followed by the university sector and institutes of technology.
Education had highest completion rates (up to 94 per cent) in areas such as health and welfare, social sciences, agriculture and veterinary.
However, computing had the the lowest levels of completion overall, with rates nationally at about 55 per cent.
Other fields with particularly low completion rates were engineering, manufacturing and construction and services.
The lowest completion rates were among higher certificate or ordinary degree courses (known as level six and seven) in areas such as computing and engineering at institutes of technology.
Civil engineering
Some of the highest non-completion rates included building and civil engineering at Letterkenny IT (86 per cent ), biology and biochemistry at IT Tralee (81 per cent) and computing at Athlone IT (67 per cent).
A significant gender gap is also emerging in the number of students who go on to complete their college courses.
The female completion rate was 81 per cent compared to 70 per cent for males.
In addition, females outperformed males on average across most fields of study, both in terms of completion rates and final grades.
The study also shows high Leaving Cert points are associated with a much higher probability of completion, while low points are associated with a much lower probability of completion.
Just under half of those who entered college with less than 300 Leaving Cert points completed their course, for example, compared with 93 per cent of those that entered with more than 500 points.
Higher grades in Leaving Cert maths and English were also found to be strong predictors of performance in higher education.
There is also evidence that students with higher points from disadvantaged or Deis schools were more likely to complete their courses compared to students from grind schools on similar points.
The data also shows that many students who failed to complete their course returned to complete other courses.
Graduate
For example, of almost 28,000 non-completers who were tracked in the study, over 17 per cent went on to graduate in another Irish higher education institution.
This proportion varied considerably and was higher at university (26 per cent) compared to institutes of technology (13 per cent).
Dr Vivienne Patterson of the Higher Education Authority said the data was vital for future planning to ensure students of all abilities have the best experience of higher education regardless of what field they study.
The Technological Higher Education Association, which represents institutes of technology, said it was clear that students with lower Leaving Cert points and from disadvantaged backgrounds were "particularly vulnerable" and required more support.
"This should inform the targeting of funding to ensure that those students who wish to complete their programmes receive the extra supports and opportunities to do so," said Dr Joseph Ryan, the association's chief executive.
He added that while the proportion of students entering institutes of technology with fewer than 400 Leaving Cert points was particularly high ( 82 per cent), some 66 per cent of students complete their programmes.
This, he said, was testament to the extra supports and tuition that are put in place to help students with fewer Leaving Cert points or low maths scores to progress successfully.
