Nurses at St Vincent's Hospital in Dublin are refusing to leave patients' bed sides this morning.
INMO union members say they are being routinely asked to carry out admin work - which gives them less time to spend on medical duties.
They have begun a work-to-rule to force management to prioritise patients and hire extra staff.
Around 100 nurses take part in lunchtime protest outside St Vincent's Hospital ED. pic.twitter.com/2FIeosPy0n— Fergal Bowers (@FergalBowers) October 12, 2015
They also say they are worried about overcrowding in the A&E and want emergency cases seen first.
Extra resources have been put in place for the duration of the protest.
"The immediate response from nurses was: 'Why did it take a notification of industrial action and notification of a dispute starting for those additional resources to be placed in the emergency department?'," said Philip McAnenly from the Irish Nurses and Midwives Organisation.
"But it's further proof that there is merit in what the nurses are saying, that the unit has been understaffed."