Four violent offenders in maximum security prison have undergone and graduated a programme aimed at helping change their behaviour.

It's the first time maximum security prisoners have carried out the programme in New Zealand.

Department of Corrections psychologist Sarah Bramhall says the programme is important for rehabilitating prisoners - and protecting the public.

"If we can work with these men to try and reduce their rates of re-offending, by doing that we're protecting the public."

Sarah Bramhall says the course will help the world be safer when they are released.

"The men who have completed the programme have enough tools and skills to be able to choose the right pathway and to choose the right behaviours whilst in prison, and going forward on their release."