Radiographers in Counties Manukau are taking industrial action.
Those at Middlemore Hospital and the Manukau Superclinic have given notice of action from Monday through to next Tuesday.
It is the latest in a series of measures being taken by medical radiation technologists nationwide and comes after nine months of negotiation.
Staff are seeking a cost of living increase of 2-3%
The Counties Manukau DHB says some services will be affected, particularly the Emergency Department where X-ray, CT and MRI scans will be operating in a reduced capacity.