Clerical and administrative staff in the Health Service Executive - who are members of the Fórsa trade union - have held protests at hospitals around the country.
The demonstrations are the latest stage in an ongoing campaign of industrial action over a recruitment freeze on certain posts.
Fórsa said the unilateral hiring pause is a breach of its collective agreements with the HSE.
Members voted overwhelmingly in support of the industrial action in a ballot earlier this year.
It was suspended for a number of weeks in the autumn to allow for engagement with management, but a breakdown in those discussions in early October led to the resumption of the campaign.
The one-hour protests took place at lunchtime outside several hospitals around the country.
Further demonstrations are planned for tomorrow afternoon, at locations not covered by today’s action.
Last month, the HSE announced that it was extending a moratorium on hiring to all categories of staff, with the exception of consultants, doctors in training and 2023 graduate nurses and midwives.
At the time, its Chief Executive Bernard Gloster said it needed to address the fact that it was on course to exceed its 2023 funded workforce target, which he described as "neither affordable or sustainable".
Fórsa's national secretary for Health and Welfare Ashley Connolly said that clerical and admin staff at the HSE are not responsible for budget overruns.
"Despite extensive engagement by Fórsa, the HSE remains unwilling to acknowledge that vacant posts must be filled," Ms Connolly said.
"At this time of year, the health services need to be fully staffed, not understaffed."
"These protests are the next step in our campaign of industrial action, providing an opportunity for health workers to voice their opposition to the continuing recruitment freeze, while minimising the effect on service delivery or service users," she added.
The HSE said it regrets that Fórsa is taking industrial action and that it will work to ensure the protection of services throughout the dispute.
"It must be noted, the Government funded the HSE to recruit to over 6,000 new posts in 2023 to support the development of services," the executive said in a statement.
"We reached that target before the end of the year, hence the temporary pause."
"During 2023 we also filled 13,000 replacement posts," the HSE added.
