The Public Service Association has released survey results which it says show tight health funding is taking its toll on staff and services.
PSA members at three Auckland district health boards were asked to rate their workload and work-life balance on a scale of one to 10, with one being acceptable and 10 being unfair or unsafe.
Out of 242 responses, half or more rated both topics in the seven to ten range.
PSA national secretary Richard Wagstaff says DHBs are having to look for savings and one common way of achieving them is not to fill vacancies, which is demoralising for workers and putting them under stress.
Mr Wagstaff says the staff shortages have also added to waiting lists in some health categories.
The Nurses Organisation says it receives messages from its members daily about the major pressures they are under at work.
Industrial adviser Lesley Harry says some people are leaving because of the pressure, and they may not be replaced.
The executive director of the Association of Salaried Medical Specialists, Ian Powell, says the findings show the health system is being expected to do too much and is under strain.
The Auckland District Health Board says it is not holding open vacancies for extended periods. It says patient safety and staff welfare are top concerns in financially constrained times.
A spokesperson for Health Minister Tony Ryall has declined to comment.