New research suggests people with serious mental health problems are dying at twice the rate of other New Zealanders.
The Otago University-led study was published in the New Zealand Medical Journal on Friday.
Researchers studied more than 266,000 people who had contact with mental health services over eight years until 2010.
They found the death rate for those whose problems were severe enough to involve the psychiatric services was twice that of others.
People with more severe illness, such as schizophrenia, had three times the death rate.
The main causes of death were natural, such as cancer and heart disease, with suicide, accidents and smoking among other causes.
One of the study's authors, Ruth Cunningham, said overseas studies have revealed similar findings, but this was the first New Zealand research on the topic.
"We need to do more investigation about why this is the case. Why is it that people with mental health problems are dying earlier than the rest of the population? But we also need to draw people's attention - the wider medical profession, the wider health services' attention - to this problem" she said.
The researchers said discrimination and poverty also played a part and coordinated action was needed to address the inequality.