Upgrade works are to begin next week on a number of wards at Mayo University Hospital.
However, the works will mean the closure of up to 38 beds at the hospital to facilitate construction.
Instead, hospital management are planning to use the acute ward at the Sacred Heart Hospital, also in Castlebar, as required.
From next Monday 17th August, upgrade works will begin on the A Ward, B Ward and Paediatric Ward at Mayo University Hospital.
The works involve replacing and upgrading windows, and replacing all the toilets and showers on the A & B Wards, and should be completed by the end of October.
Hospital management has confirmed that up to 38 beds will be out of use to facilitate the construction works, and the hospital is planning to use the acute ward at the Sacred Heart Hospital as needed.
The acute ward in the Sacred Heart Hospital will be under the clinical governance of Mayo University Hospital, with consultants and nursing staff from the hospital caring for patients there.
General Manager Catherine Donohoe told Midwest News that the upgrade works are long-awaited, and they're happy the works are finally progressing.
She acknowledged that there will be some noise and disruption during the works, and has apologised in advance to patients, their families and staff.
She says every effort will be made to minimise the impact of the construction work on patients in the hospital.