Part of Ashburton hospital is being shut, following an engineering assessment that shows two buildings are at risk of collapse in an earthquake.
Canterbury District Health Board says one of the buildings is used for outpatients and the other for physio and occupational therapy services.
The board says the buildings, which were built in 1879 and 1880, are made of unreinforced masonry, and considered a high seismic risk.
It is taking urgent action to close them, after receiving a report from engineers on Monday.
Corporate services general manager Murray Dickson says employees are relocating to another part of the hospital.
He says there will be disruptions for a few days, but hopes appointments will be back to normal by the end of the week.