To show the 12 month prevalences of mental disorders, 12-month treatment contact and use of mental health services among Cook islanders resident in New Zealand.(A) The New Zealand Mental Health Survey (NZMHS) is a nationally representative face-to-face household survey, carried out in 2003-2004. It surveyed 12,992 New Zealand adults aged 16 or more including 2374 Pacflc peoples (500 Cook Islands Maori) and 2457 New Zealand Maori. (B) An extract from the Mental Health Information National Collection (MHINC). This is a national dataset that is reported to by mental health services around New Zealand.Multiple logistic regression models are used to produce estimates from both sets of data. In the case of A) the NZMHS the results are weighted to account for different probabilities of selection and analysis takes account of the complex survey design.A previous paper and this one confirm that Cook Islanders experience high prevalence of mental disorders. However the difference is more attributable to their population age and gender structure or being New Zealand-born than from ethnicity. The prevalence was higher among New Zealand-born Cook Islanders than those born in the Cook Islands. Those born in the Islands with a disorder were less likely to have used a health service for their mental health compared with others and much less likely to have visited a specialist mental health service. From MHINC, twelve month data on use of mental health services shows: high use of acute inpatient and Forensic mental health services by Cook Island clients but similar levels of community mental health services. Cook Islands clients were more commonly diagnosed with bipolar psychotic or schizophrenic disorders. They were also more likely to be diagnosed with a substance disorder.In spfte of high levels of disorder Cook Islanders have low use of specialist mental health services. The exception to this is an over-representation in inpatient and forensic services. This experience of mental health services at the extreme end implies delayed or avoided treatment that has resulted in more serious levels of disorder among those Cook Islanders who are eventually seen by mental health services.