More than 250,000 people are waiting for health scans in hospitals.
According to figures from the the National Treatment Purchase Fund, 59,000 have been on the lists for over a year.
These new figures relate to the number of people waiting for outpatient scans in acute hospitals.
The scans are CTs, MRIs and ultrasounds.
At the end of the last year, there were 251,000 people on the waiting list.
They include 38,000 people who have been waiting over 18 months.
Sinn Féin's Health Spokesman David Cullinane said the figures are shocking.
"We know that, separate from diagnostic waiting lists, we have just under 900,000 people on some form of hospital or acute hospital waiting lists," he said.
"Separate from that we have over 230,000 people who are on community waiting lists.
"To have just over 250,000 people waiting for a scan of some description, it's incredible that we have the amount of people waiting for a scan that we do," he added.
The HSE said the figures relate to the number of people waiting for new appointments or return/planned/surveillance scans.
It said not all patients listed are waiting for access to a diagnostic scan.
The HSE said funds have been provided to address the waiting lists this year.