The Corrections Department is crediting better staff training and prisoner assessment for a drop in recorded incidents of self-harm in jails.
Figures released to Radio New Zealand under the Official Information Act show 2,030 incidents of self-harm in jails in the past five years.
Two years ago, there were 433 incidents of self-harm in which the department thought there was no threat to life; so far this year, there have been 92. The number of cases in which life was considered to have been under threat has fallen from 38 to 17 in the past year.
The department says the prison suicide rate has dropped by nearly 60% since 1996.