Up to 65 radiographers from one of New Zealand's busiest hospitals began a four-day strike on Thursday.
The strike at Auckland's Middlemore Hospital is part of industrial action by radiographers nationally over pay.
The action at Counties Manukau District Health Board follows suspensions of radiographers in Auckland this week.
Another three-day strike is planned at Auckland City Hospital on 3 September and a national day-long stoppage on 7 September.
Counties Manukau DHB says it has deferred non-urgent surgery for up to three-quarters of cases during the next two to three days in preparation for the strike.