The intensive care unit at University College Hospital, Galway, is being relocated temporarily, due to discovery of an air-borne fungus in the premises.
The organism is common, is not life-threatening, and does not affect healthy people, according to a spokeswoman for hospital management.
The aspergillus organism is not linked to the superbug which was discovered recently in St James's Hospital in Dublin, she added.
Hospital management decided to relocate the unit because the fungus - which is similar to a mildew - can cause infection in vulnerable people and poses some risk, the spokeswoman said.
It may result in some patients having their admissions rescheduled, but all urgent and emergency intensive care unit and hospital services would continue to be provided, she said.
The seven-bed unit is being moved to another area of the hospital where an £80 million construction programme is in progress.
The development work is due for completion in 2003.