The organisation that represents scientists who carry out critical diagnostic testing of patient samples in acute hospitals, including for Covid-19, is to ballot members for industrial action.
It follows an overwhelming vote in favour of such a ballot at a recent annual general meeting of the Medical Laboratory Scientists Association (MLSA).
Medical scientists say they are not satisfied with the progress being made on achieving parity with scientific colleagues who work in biochemistry labs.
In January, 96% of MLSA members rejected the public sector pay agreement, Building Momentum, because they felt it was insufficient to deal with problems in the sector.
Further talks have since taken place about their grievance on pay and career development, dating back to 2002, but no agreement has been reached.
"Medical Scientists have patiently waited their turn, while responding to all of the clinical and professional challenges that have arisen for the twenty years since this grievance arose, but we will wait no longer," MLSA chairperson Kevin O'Boyle said.
"The MLSA has taken full industrial action only once in its 60-year history so this is a big step, but we are now left with no alternative."
The union says it remains open for talks around how issues with recruitment and retention can be addressed.
Currently, the union claims, there are 130 medical scientist posts vacant around the country, caused by inferior pay, conditions, career structure and opportunities.
The MSLA represents around 1,800 staff in public, Health Service Executive and private hospitals as well as the Irish Blood Transfusion Service.
Medical scientists received pay parity with other scientific colleagues in 2001, but lost it through an unintended procedural issue in 2002 that arose because of the benchmarking process and now receive on average 8% less.