Strikes by stand-in doctors could close at least six hospital emergency departments.
Locum staff are unhappy their pay has been cut from 40 Euro to 34 Euro an hour and are refusing to turn up for shifts.
Yesterday Letterkenny University Hospital was one of the hospitals affected by the move.
The Irish Association of Emergency Medicine warns the action could spread to other hospitals.
Association spokesperson and Sligo consultant Fergal Hickey admits that patients are likely to suffer: