The HSE says the Emergency Department at Sligo University Hospital is extremely busy today.
It is reminding the public to only attend the Emergency Department in the case of a real emergencies and to contact their GP or GP Out-of-Hours service in the first instance.
A spokesperson says the industrial action by the Irish Nurses and Midwives Organisation is having a significant impact on patient services across all of the hospitals in the Saolta University Health Care Group, including Sligo.
The industrial action is taking place at all public hospitals, healthcare facilities and community healthcare services until 8am tomorrow morning.
The HSE says it is continuing to work with the INMO on arrangements for the day to ensure safe service provision. Scheduled outpatient, inpatient and day surgery appointments have been cancelled.