The Health Service Executive has said there were over 1,500 cancellations of procedures as a result of industrial action by nursing unions today.
Nurses staged one-hour work stoppages at 22 hospitals and health facilities in their continuing dispute over pay and conditions.
Facilities in Ballinasloe, Castlebar, Cork, Drogheda, Limerick, Wicklow, Dublin, Navan, Tralee, Tullamore and Wexford were affected.
The HSE, meanwhile, says it continues to have serious concerns about the risk to patient safety arising from next week's planned stoppages.
It says at present more than 3,000 patient appointments-procedures are at risk and over 1,500 have been confirmed as cancelled.
The HSE says it is continuing to seek meetings with the nursing unions in order to secure exemptions in critical areas such as cancer, cardiac care and emergency care.
The Minister for Health, Mary Harney, has said patients are being put at risk by the ongoing nurses' dispute.
She said appointments are now being cancelled at a number of hospitals and people should be in no doubt that the situation is very unfair.
Ms Harney said it was not possible for nurses working a 39-hour week to be paid the same money to work 35 hours.
She was speaking at a Progressive Democrat press conference in Dublin today where a small number of protestors from the Irish Nurses Organisation had gathered outside.
As she left the press conference Ms Harney spoke briefly with one of the protestors who said that patients were suffering because of inaction by the present Government.
The Health Minister said she did not accept this argument, and she did not accept that nurses were being treated less favourably than other groups of workers.
Meanwhile, the head of the Psychiatric Nurses Association has criticised both the Government and the Opposition over the nursing dispute.
General Secretary of the PNA Des Kavanagh warned there could be electoral consequences.
Other two and three-hour stoppages are set to take place next Tuesday, Wednesday and Friday.
The Health Service Executive earlier warned that thousands of patients will be affected by the escalating industrial action by nurses seeking a pay rise and a 35-hour working week.
The HSE added that plugging gaps is getting harder as many replacement staff are too tired to do more overtime.
They are now 'actively considering' cutting nurses' pay to offset the estimated €2m a week cost of their action.
Some hospitals see up to 1,000 outpatients a day and losing half a day means cancellations for up to 500 patients per hospital.
The HSE is asking patients to turn up for appointments, unless advised otherwise.
They should also avoid Accident and Emergency units unless absolutely necessary.
