Ms Pilott said feedback from staff was the the number of threats received had increased and become more aggressive.
"The issue of threats being made against staff is an ongoing concern at agencies such as ACC and it is regularly raised at internal health and safety meetings," she said.
Police investigated a threat in Auckland when a client phoned ACC's call centre after his review hearing and said his case manager "was lucky he didn't shoot her".
Another staffer was at a hearing review in Rotorua when the reviewer had to warn the client about abusive and aggressive behaviour towards them.
So far this fiscal year, there has been only one serious incident when a staff member was assaulted by a client at an Auckland hearing.
ACC declined to give any further information on the assault because it was still being investigated by police.
Labour's spokesman for ACC Andrew Little said the threats were a "hazard of the job" and he knew staff who had left the organisation because of it.
He felt threats could be minimised if ACC provided trauma counselling to clients from the outset and they were given a clear understanding of ACC's role.
However, an ACC spokeswoman said the number of threats received by the organisation each year was small and worked out to about one threat for every 6000 claims.