Members of the Public Service Association (PSA) at all six South Island DHBs began a one-hour strike at 8.30am today.
PSA assistant national secretary Warwick Jones said staff were striking to protest against being paid less than North Island staff doing the same work.
South Island staff received an annual base salary of $27,641, compared with $30,500 for North Island staff, he said.
"It's unfair to pay workers less for doing the same work simply because they live in the South Island," Mr Jones said.
"The Government needs to acknowledge this discrimination and work with the DHBs to bridge this pay gap." Administrative workers provided essential support to clinical staff, he said.
The walk-off this morning follows a one-hour strike on Friday afternoon.
Chris Fleming, spokesman for the DHBs involved, last week said contingency plans had been put in place to minimise disruption.
It was disappointing that staff had decided to express their views by walking off the job, he said.
