Some 800 nurses and midwives from across the country are protesting outside the Nursing and Midwifery Board of Ireland (NMBI) in Dublin against registration fee hikes.
The Irish Nurses and Midwives Organisation (INMO), SIPTU and the Psychiatric Nurses' Association (PNA) all say a planned 50% increase in the €100 annual fee paid by their members every year is "unjust".
They say registration for other health professionals will remain unchanged until at least 2017.
The three unions say the NMBI currently "does not enjoy the support and confidence of the professions it is established to regulate."
"In fact the view of the vast majority of nurses and midwives is that the board charges them a registration fee, annually, only to fund the legal costs, in fitness to practice hearings, when difficulties in the clinical environment are being investigated," they add.
The INMO General-Secretary Liam Doran says his members will not pay the increased rate.