Nurses and midwives will hold lunchtime protests across the country today against an increase in fees.
It comes as the General Secretary of the INMO, Liam Doran, says his members will not be "intimidated".
Members of the INMO, SIPTU and the Psychiatric Nurses Association say no services will be affected by the demonstrations.
They will take place in Dublin, Cork, Sligo and Drogheda.
Nurses have called for the proposed 50% hike to the annual retention fee to be scrapped.
They say they have been targeted by the Nursing and Midwives Board with letters telling them they will not be allowed to work if they do not register.
Mr Doran said: "I think the approach ahs been very regretful, I think there has been an atmosphere of sort of a 'we've made a decision now, just do it'.
"There's been no consultation with the profession before the increase in fee was announced, there's been no consultation with the profession since."
"I think the board has sought to intimidate nurses and midwives into paying" he added.