This paper describes demographic and diagnostic data for people admitted to three psychiatric units in Auckland, New Zealand over the year 2000. Methods: A retrospective file review of 932 people involving 1232 admission episodes was conducted in the acute adult inpatient psychiatric units of west, north, and south Auckland. Patient characteristics, diagnosis, and interventions were recorded. Results: Overall, 62% were involuntary admissions and the most common diagnosis was schizophrenia (38%). Based on the community population, Maori admissions were double the expected rate and Asian admissions were lower than expected. Compared to European admissions, Maori, Pacific, and Asian admissions were all more likely to have a diagnosis of a psychotic disorder. In addition, Maori were more likely to be admitted involuntarily than Europeans. Conclusions: Variations in psychiatric inpatient representation, diagnosis, and compulsory treatment were found across ethnic groups. The explanations for ethnic differences in mental health are likely to be many and multifactorial including socioeconomic status, pathways to access of care, levels of family understanding and acceptance, and community capacity to manage less disruptive presentations. The findings provide a benchmark for recently established ethnic specific Maori and Pacific community mental health services. A follow-up study is recommended to review utilisation of community services for patients following an admission