The Department of Agriculture rehired 59 veterinary inspectors after they retired earlier this year.
Fianna Fáil TD and spokesperson on health Billy Kelleher said the same is true for dozens of retired staff within the public sector, including some assistant secretaries-general.
He obtained the information through a series of Dáil questions.
Earlier this year, thousands of civil servants retired to take advantage of favourable pension entitlements available to them up until the end of March.
On RTÉ's Morning Ireland, Mr Kelleher said the rehiring of these staff was preventing existing staff from being promoted from within the civil service.
He said the vacancies created by the retirements present a perfect opportunity to remove people from the live register.
"It is clearly evident that across large sectors of the public sector and the civil service there is rehiring of people who have retired,” he said.
“I just believe this is unacceptable in this day and age where we have 440,000 people unemployed and many of them with skillsets - highly qualified and well motivated people.”
Responding to criticism of the rehiring of retired staff, Minister of State at the Department of Public Expenditure Brian Hayes said that the short-term re-employment of retired civil servants is a "cost saving measure" in the long run.
He said that by bringing back people with particular expertise for six to 12 months, departments were saving on extensive, external searches for new staff.
He said that wherever possible, people who are out of work should be given priority when vacancies arise and in most cases this is what happens.
The Government would be keeping an eye on this, he said.