The Salvation Army is talking to the Ministry of Health about more funding to run addiction treatment courses for the Mongrel Mob.
Four years ago, the Notorious chapter of the gang knocked on the Salvation Army's door, worried about the deaths of members from methamphetamine overdoses and the example their addiction was setting for children and grandchildren.
Since then 50 members have been through the eight-week residential course to overcome their addiction to methamphetamine and learn life skills such as parenting.
While some have since fallen off the wagon, the Salvation Army says many have attended a later course and stayed drug free.
National addiction manager Jerry Walker said one graduate was proud of the fact he had been out of jail for 12 months. "You might not think (that) is a big deal, but for the previous 20 plus years he'd been in prison every year, in and out, and for him and his family that was actually a significant achievement."
An outside evaluator is reviewing the programme's success and the Salvation Army hopes the Ministry of Health may agree to fund more treatment programmes.
Mr Walker said that at $90,000 per prison inmate per year, a course that may keep people out of jail represents value for Government money.