Men aged 35 to 39 and women aged 15 to 19 have the highest rate of hospitalisations for intentional self-harm, Ministry of Health figures show.
In 2007, 2,678 people were treated in hospital for longer than 48 hours after intentionally harming themselves, a fall from 3,030 in 1996.
The Ministry of Health shows women are twice as likely as men to be hospitalised for intentional self-harm.
The rate of self harm hospitalisations for Maori was about 75 people per 100,000 compared with about 62 per 100,000 for non-Maori.
The ministry's mental health director Dr David Chaplow says suicide prevention initiatives are continuing to be implemented, such as improving follow up care for people at risk and increasing community understanding about depression.