The paper analyses geographical variations in use of acute psychiatric inpatient services within New York City and how these have changed from 1990 to 2000. We review literature suggesting reasons for the variations observed. Data from the New York State Department of Health Statewide Planning Research and Cooperative System were combined with population census data to produce age standardized ratio indicators of admissions and of bed days, as measures of use of general hospitals for psychiatric conditions, by males aged 15-64, in Zip Code Areas of New York City, in 1990 and 2000. Geographical variations in hospital use were related to proximity to general hospitals with psychiatric beds and to socio-economic status of local populations (as recorded in the 1990 and 2000 population censuses). Areas close to psychiatric hospitals areas show high admission levels. Controlling for this, Zip Code Areas with higher concentrations of poverty, of African American residents or of persons living alone were associated with relatively high admission ratios. These relationships vary somewhat between diagnostic groups. Area inequalities in standardized admission ratios persisted and widened between 1990 and 2000, and the highest hospital admission ratios were increasingly concentrated where social and economic disadvantage was greatest. Various possible reasons for this trend are explored. We conclude that increasing intensity of poverty in disadvantaged areas is not likely to provide an explanation and that the trends are more likely to result from changes in hospital management and funding affecting access to hospital services.