Around 200 nurses have walked off the job in Whanganui, demanding fairer pay and safer working conditions.
Nurses rostered to work on Wednesday instead gathered at the Cobham Bridge roundabout armed with flags and picket signs from 11am.
Whanganui nurse and NZNO member Carmel Scott said the action was a last resort for nurses.
"A lot of people think this is about money, but this is also about safe staffing.
"People just want to be able to go to their job, do a job right and take care of their patients. With the staffing and lack of nursing we have at the moment, that's not possible."
"We're hopeful that this will change the offer, that's what this is all about."
Whanganui DHB confirmed on Wednesday that 112 appointments were rescheduled due to the strike across the outpatient, surgical, and radiography departments.
NZNO national organiser Manny Down said that while the NZNO is conscious that the strike would affect some levels of patient care, steps have been taken to ensure fundamental care is still available.
"Patient care is always at the top of our minds. If there's an emergency, they can call us and we will go and assist with life-preserving services. We have contingency plans.
"Ultimately it is about safety, and we want to ensure everyone is safe."
The strike comes after negotiations with the New Zealand Nurses Organisation and a collective of all 20 DHBs broke down, with union members resoundingly voting against a proposed 1.4 per cent pay increase.
Further negotiations last week led to the DHB collective adding a $4000 lump sum - a part payment on back pay that would be owed to members through a pay equity claim.
However, the amended offer failed to sway union members, with strike action subsequently confirmed for Wednesday.