Dozens of services have been cancelled today by Bus Éireann "due to operational issues".
The routes affected are predominantly in counties Mayo, Galway, and Sligo. Some services between Dublin Airport and counties Waterford and Wexford have also been cancelled.
Intending passengers are asked to check the Bus Éireann twitter account for updates.
In a statement, the company apologised for any inconvenience caused and said it is actively recruiting for drivers throughout the country.