The Mid-Western Health Board has announced the closure of the kitchen and canteen at St Camillus's Hospital in Limerick city as a "precautionary measure" because rats were sighted on the premises.
Contingency measures are being taken to cater for the 280 mainly elderly patients.
Mr John Hennessy, the general manager of the board, said: "The safety of patients and staff is paramount in a situation like this and immediate precautions were taken, including the disposal of all food that might have had a potential exposure, and alternative catering arrangements were made for patients and staff."
A pest control firm caught three rats on Tuesday evening and sterilised all equipment, walls, surfaces and utensils.