Projections for the prevalence of psychiatric disorders were calculated for the estimated population between 17 and 64 years of age in Puerto Rico for the year 2000. These projections were based on the results of an epidemiologic research study conducted in 1984 using a community based sample and the population estimate for the year 2000. The psychiatric disorders included affective and anxiety disorders, somatization, schizophrenic disorders, and alcohol abuse and/or dependence. The prevalence of each of these disorders will increase by the year 2000. The prevalence of affective and anxiety disorders, in particular, will have a relative increase of 5%. The simultaneous increase in the prevalence of psychiatric disorders and the increase in the population will have the combined effect of increasing the number of expected psychiatric cases by 25%.