There are 37,000 members of the Irish Nurses and Midwives Organisation taking part in their second 24-hour strike.
Pickets are in place at 240 locations around the country.
An estimated 27,000 patients or service users are affected by the action.
RTÉ News spoke to some of those who are on strike.
University Hospital Galway
Nurses on the picket line outside the hospital say they do not want to be on strike, but are doing so for patients and patient safety.
They say they are "used to working in bad conditions" and cannot always give the care that they want to give.
St Angela's College Sligo
Edel McSharry, who is the head of the Department of Nursing at the college, says she believes the only way to resolve the dispute is to pay nurses the same as other healthcare professionals.
She says nurses spend four years in training to secure the level of knowledge they need to do their job and to not be paid on a par with their colleagues when they qualify is "not fair".
St James's Hospital Dublin
Nurses on the picket line outside the hospital say they could "work in a supermarket" with less responsibility "for the same money".
University Hospital Kerry
Jane Walsh works in the hospital as a clinical nurse manager on the surgical ward.
She says the future of the nursing profession and the health service is under threat because working conditions have become "unsustainable".
Nurses' strike causing 'significant disruption' to services - HSE
Salaries are key to ending nurses' dispute - INMO
Nurses' dispute: Not just deadlocked, but escalating
'I'm sick with upset' - A patient's view of nurses' strike