Patients at Whanganui Hospital will be limited to two visitors at a time and some appointments have been postponed.
Whanganui District Health Board put the measures in place as part of the national Covid-19 response.
The number of visitors for patients in the critical care unit or visiting those receiving end-of-life care will be on a case-by-case basis.
Visitors will be asked for their contact details in case they need to be contacted.