Nurses and midwives suffered almost 3,500 assaults over the last six years, according to the Irish Nurses and Midwives Organisation.
Speaking at the Irish Congress of Trade Unions conference in Belfast, INMO General Secretary Designate Phil Ní Sheadhgha said 66% of those 3,462 assaults had taken place not in the psychiatric service but in the general health service.
She warned that the assaults were a direct consequence of poor workforce planning and would get worse until the Health Service Executive got the staffing numbers right.
The HSE spent €77 million in agency staff in the first 18 weeks of this year, she said, which was described as a scandal.
All unions representing health professionals knew there was a staffing crisis, Ms Ní Sheadhgha said, but the answer in the Republic was do not employ, or employ on an agency basis or a precarious contract.
Agency work was bad for workers and patients and was not the way to plan for the future, she added.
Meanwhile, INMO General Secretary Liam Doran said there were 51,300 patients on trolleys in Irish hospitals in the first six months of this year, with 344 on trolleys at 8.30am this morning.
He said resolving the problems would involve not just demanding more resources, but said that staff would also have to be prepared to change, work smarter and work better.
Mr Doran also accused the hospitality sector of profiteering from the €650 million they received from the 9% VAT rate. He called for that money to be diverted to the health service.