Objective: To help predict changes in patterns of service delivery, the total number of inpatient admissions to specialty mental health organizations and the number of elderly persons ( over age 65) admitted were projected in five-year intervals between 1990 and 2010. Methods: One set of projections is based on 1986 rates of use and their coefficients of variation. A second, more accurate, set is based on 1990 rates derived from logarithmic projections of trends from 1980 to 1 986 and the coefficients of variation for the 1986 rates. Results: Projections based on 1990 rates show an increase of more than 25 percent in the total number of inpatient admissions to all specialty mental health organizations between 1986 and 2010 and an increase of more than 40percent in elderly admissions. Nonfederal general hospitals are expected to have the largest increases in the number of total admissions, and state and county mental hospitals the smallest. The greatest percentage growth in total admissions will occur in private psychiatric hospitals. For elderly persons, inpatient admissions to Veterans Affairs medical centers will show the largest percentage increase, and admissions to state and county mental hospitals the smallest. By 2010 the majority of elderly admissions (67.6percent) will be to nonfederal general hospitals. Conclusions: Plans to cope with increased demand for inpatient services should take into account the potential economic consequences of the forecasted changes as well as their effects on allocation of and access to services.