Irish Rail has cancelled its services between Dundalk and Belfast on Friday as Northern Ireland public sector workers take industrial action.
The strike is over spending cuts in the civil service, with over 60,000 members of trade unions expected to take part causing disruption to transport, health services and schools.
All Irish Rail Enterprise services have been cancelled between Dundalk and Belfast, with Irish Rail spokesman Barry Kenny saying "the Northern Ireland network is effectively shut down for the day".
Scheduled Enterprise services between Dublin Connolly and Dundalk will operate at 7.35 am, 1.20pm, 4.50pm and 7.00pm while Enterprise services from Dundalk to Dublin Connolly will operate at 8.00am, 11.48am, 5.20pm, 10.48pm.
Dublin to Dundalk commuter services will be unaffected.
Services are expected to be back running as normal tomorrow.