Sociodemographic variables obtained from 1986 census data were used to calculate the Jarman index (a measure of underprivilege) for census area units of Auckland. The index was found to correlate with psychiatric admission rates for the years 1982-6 suggesting it might have some utility as an indicator of demand for mental health services. However, the highest admission rates were from particular central city areas reflecting the presence of a deinstitutionalised patient population with chronic mental disorder. This group would appear to require independent assessment of their needs and specific allocation of resources. Factor analysis of the census variable scores comprising the Jarman index revealed principal components equatable with poverty, living without adult company and transient residence.