Mayo General Hospital is to review almost 13,000 prostate cancer test results.
The review was confirmed tonight, after it emerged that the kit used to test for the disease was faulty.
It's feared inaccurate test results may have led to a number of men having unnecessary biopsies.
The testing kit at the centre of the controversy is manufactured by Siemens and it's used to detect the level of PSA protein in the blood as an early indicator in prostate cancer.
Tonight, Mayo hospital confirmed it had used the kit between July last year and June this year, when it was recalled because it was reading up to 23 per cent higher than other tests.
The hospital says it has contacted all GPs who ordered the PSA tests and offered to retest their patients.
It says it is ready to review all 12, 866 tests that were conducted using the faulty kits to establish how many had an elevated reading, and to decide on further action.
The Siemen's test was also used by James Connolly Hospital in Dublin.
However it's not known if any other Irish hospitals used it.