The "Viennese Instrument for Suicidality in Correctional Institutions" (VISCI) presented here is based on the results of a large case-control study and on research on literature examining suicide prevention in general and in the prison population in particular. The aim of this study was to validate the properties of the VISCI to differentiate between suicides and nonsuicides. The sensitivity and specificity of the VISCI was tested in the files of 55 correctional suicides, and 110 controls. VISCI differentiated well between suicides and nonsuicides. The routine administration of the VISCI may help to direct the existing professional attention to inmates with the highest need.