A prospective research study attempted to identify persons who would subsequently commit or attempt suicide. The sample consisted of 4,800 patients who were consecutively admitted to the inpatient psychiatric service of a Veterans Administration hospital. They were examined and rated on a wide range of instruments and measures, including most of those previously reported as predictive of suicide. Many items were found to have positive and substantial correlations with subsequent suicides and/or suicide attempts. However, all attempts to identify specific subjects were unsuccessful, including use of individual items, factor scores, and a series of discriminant functions. Each trial missed many cases and identified far too many false positive cases to be workable. Identification of particular persons who will commit suicide is not currently feasible, because of the low sensitivity and specificity of available identification procedures and the low base rate of this behavior.