The drug treatment unit at Otago Corrections Facility marked its 50th graduation yesterday.
Five hundred and thirty-six prisoners have graduated from the drug and alcohol rehabilitation programme since it started in 2010.
One of the 10 prisoners graduating yesterday said ''the course changes the way you think around your addiction and makes it clear that with help you can become a better person in yourself''.
Prison manager Jack Harrison said ''this is a significant milestone for Corrections, the prisoners graduating and for the community''.
''By tackling drug and alcohol abuse, we're giving people a shot at a better life and, in turn, we're giving the people of New Zealand a better community to live in.''
