A mental health network says Maori are over-represented in the system and putting them into seclusion - meaning a bare, locked room - is not a therapeutic treatment.
Ministry of Health figures show that Maori are much more likely to be secluded than non-Maori mental health patients.
In 2012, 882 people were secluded within the mental health system of which Maori made up 32%.
The ministry says it has a five-year plan for eliminating the seclusion of Maori patients.
Seclusion is used for the personal safety of patients and the security of health workers. Patients are put in a bare, locked room and kept under observation through a window and their families are kept away.
The Platform Trust, a national mental health network of community organisations, says seclusion is a frightening and terrifying experience.
Chief executive Marion Blake says there is no evidence to suggest that Maori are more violent than non-Maori and seclusion is not a therapeutic treatment.
"Imagine when you're frightened and you're really unwell, being locked away in an isolation room. I think seclusion in itself is something that we really need to address, and to be fair, the numbers are coming down, but we're still using it as a treatment."
The system of seclusion is not used in residential mental health services run by Te Runanga o Kirikiriroa in Waikato.
Mere Balzer of the runanga says the average person views Maori as being aggressive and that perspective is being taken into hospitals.
However in its mental health services, Mere Balzer says, they find other ways to talk people out of their anger in a home-like environment. She says patient interaction with staff is informal and has a whanau feel.
Ms Balzer concedes some young Maori men can appear intimidating, because they're well built and are defensive, but questions whether seclusion is a legitimate treatment in today's world.
Health research organisation Te Pou says it doesn't know all the reasons why Maori are secluded more than non-Maori.
But a clinical advisor at Te Pou, Anne Brebner, says cultural issues aren't on the top of everyone's list of priorities when people seek treatment for mental health problems.
She says more work needs to be done to find out why rates of Maori seclusion are so high.
Seclusion can be used under section 71 of the Mental Health (Compulsory Assessment and Treatment) Act 1992.
