Crisis counselling service Lifeline Aotearoa says it is running out of money and without millions of dollars of donations it will close next year.
Lifeline has been running for 52 years, answering up to 15,000 calls a month on its 24-hour a day helplines.
People call on a raft of issues including loneliness, family violence, financial concerns, homelessness, bullying and relationship issues, mental health and suicidal thoughts.
Last year it lost government contracts and has had to cut a third of its staff.
It said appeals for government and private funding have failed.
Lifeline chairman Ben Palmer said it needed donations of $3 million in the next year and $2.5m the following years.
Mr Palmer said Lifeline was a unique service and should not be allowed to close.
He said a record 564 people committed suicide last year, a significant social and economic burden on the country.
While there were numerous other helplines, none had the expertise of Lifeline in regard to suicide, crisis, peer-support and other counselling, he said.
It was also the country's most significant specialist provider of suicide intervention and training and, as such, was on the frontline of suicide prevention in New Zealand.
Mr Palmer said with the well documented crisis in mental health and the New Zealand suicide rate reaching epidemic proportions, the Lifeline service had never been more critical.
"564 Kiwis died by suicide last year, the highest number on record and nearly double the annual road toll, which stood at 321. For young New Zealanders, particularly Maori, suicide is the leading cause of death.
"Sadly, it's estimated for every person who commits suicide 40-100 people attempt it.
"Interestingly the government is prepared to invest $666,667 per person saved from road death or serious injury - 900 people - over 10 years. In that time, based on current numbers, 5640 Kiwis may die through suicide. How much additional money is the government prepared to invest for them?"