Health workers from the Royal Hobart Hospital will stop work and hold a rally at state parliament at 11.30 on Saturday as negotiations with the government threaten to break down.
The Tasmanian branch of the Australian Nursing and Midwifery Federation said it received a disappointing initial offer from the state government on Friday after months of bargaining.
"While there were elements of the offer that were positive, key priority matters were not included," branch secretary Emily Shepherd said.
"Members overall were disappointed ... as they feel the offer doesn't appropriately respect nurses and midwives (or) value them for the work that they do."
A particular sticking point for the union is the restriction of an offer of five personal impact days to only some of the workforce.
Only emergency, ICU and mental health members would be entitled to the five extra days of leave, designed to help workers cope with traumatic situations, the union said.
"Midwives face supporting mothers as they deliver stillborn babies ... medical oncology members support those receiving treatment for cancers," Ms Shepherd said.
"Failing to apply this entitlement to all nurses and midwives shows a lack of insight."
Recruitment and retention concerns are also front of mind for the union after the government's wages offer.
Ms Shepherd says the offer would leave the vast majority of Tasmanian nurses and midwives as the worst paid in Australia, creating even more vacancies.
The state government says it is committed to delivering a fair and affordable pay rise and improved conditions for nurses and midwives.
A spokeswoman said the government was working constructively with the union to resolve negotiations as quickly as possible.
The Labor opposition says the state's health system - and workers' pay and conditions - will continue to lag while the government cuts millions of dollars from the sector's budget.
The parties will return to the negotiating table in the coming week, with the union saying it needs significant progress towards its demands to consider calling off further industrial action.