A man who sustained severe injuries in the earthquake is still in a critical condition in Christchurch hospital.
Canterbury District Health Board says several other patients with less serious injuries are in a stable condition.
The DHB says hospitals and the 24-hour medical centre had a steady night and are functioning normally, despite continuing aftershocks.
Canterbury's chief medical officer of health says the hospital system has coped well.
Dr Alistair Humphrey says it's now important to make sure the hospital system is not overwhelmed, so it is important that people go to their normal doctor for treatment for minor injuries and illness.
Dr Humphrey says it's also important that residents remember to use boiled water because unboiled tap water could be contaminated.