Southland hospital is asking the people of Invercargill to visit the emergency department only if it is an emergency.
The hospital says it is struggling more than usual at the moment with staff shortages in the department.
It has four permanent senior trauma specialists, but needs another two and is also short of locums (temporary personnel).
Southern District Health Board says it is not helpful not to overload the emergency department unnecessarily.
Chief medical officer David Tulloch says if it is not truly an emergency, people should go to general practitioners and after-hours GP services to ease the load on the department.