Police say charges have been laid in connection with a riot at Spring Hill prison in Waikato in June.
More than 20 prisoners went on a rampage on 1 June, destroying property and starting fires.
Police say 23 inmates face 41 charges, including rioting, assault, injuring with intent to cause grievous bodily harm and arson.
The Corrections Department says 117 inmates were relocated to other prisons after the riot because of the damage to Spring Hill, where repairs are underway.
The department says it will not comment on the final cost of fixing the damage until an investigation has been completed.