Major depressive disorder is the most common diagnosis in patients who complete suicide. For some time, researchers have attempted to identify factors predictive of suicidal risk in depressed patients. A principal source of such information is the National Institute of Mental Health Collaborative Program on the Psychobiology of Depression. This 10-year study, which included 954 patients with major affective disorder, found that panic attacks, severe psychic anxiety, global insomnia, moderate alcohol abuse, loss of pleasure or interest in life, and diminished concentration were predictive of suicide risk within the first year after entry into the study. Hopelessness, suicidal ideation, and a previous suicide attempt were predictors of suicide after the first year. These data allow the clinician to weigh various symptoms in terms of their potential impact on suicide in a depressed patient. Because of the particularly high risk of suicide associated with depression and symptoms of anxiety, the recognition and treatment of anxiety during the depressive episode is a particular challenge.