Lobby group Rethinking Crime and Punishment says that release and reoffending rates of inmates from Maori "focus units" in prisons are promising.
Just over a quarter of inmates released from the Maori focus units in the 2010 -2011 year re-offended within 12 months.
Department of Corrections staff say that of the 400 prisoners who served their time in five Maori Units, 108 went back to prison.
That re-offending rate is slightly lower than for inmates in other parts of the prisons.
Rethinking Crime and Punishment director Kim Workman says Maori focus units appear to show promise but have a long way to go.