The reliability of the Adult Suicidal Ideation Questionnaire (ASIQ) is examined in a sample of 325 adult psychiatric outpatients. The ASIQ is a 25-item adult form of the Suicidal Ideation Questionnaire. Internal consistency reliability of the ASIQ was high for all groups & of sufficient magnitude to suggest accuracy for clinical & research applications. High test-retest reliability was also shown for patients with affective & anxiety disorders.