Picket lines took place outside Craigavon Area Hospital, Lurgan Hospital, Portadown Health Centre and Banbridge Health Centre.
The workers are striking over a proposed 4% pay offer which they say is well below the level of inflation.
NIPSA Deputy General Secretary, Pádraig Mulholland, said: “"We must have inflation busting pay rises for all health service workers and an end to the chronic understaffing that puts lives at risk.”
9. Getting set up for the picket line
Health workers at Lurgan Hospital were joining colleagues on a 24 hour strike on Monday. Photo: Contributed
10. Flying the flag for NIPSA
Health workers at Craigavon Hospital on Monday staged a 24 hour strike over a dispute on pay. Photo: Paul Cranston
11. Waving the flag for fair pay
Health care workers at Lurgan Hospital staged a 24 hour strike over pay on Monday. Photo: Contributed
12. Unions unite during strike over fair pay
NIPSA and Unison members were among hundreds of health care workers from Craigavon Hospital and the Southern Health Trust who staged a 24 hour strike on Monday over pay. Photo: Paul Cranston