BACKGROUND An international symposium evaluated current knowledge of the epidemiology, psychobiology, and effects of medical treatment on suicidal behavior. METHODS Moderators summarized the main findings and conclusions of the participants on the basis of presentations and consensus statements at the meeting. RESULTS Despite striking advances in the medical treatment of mood disorders in the past half-century, rates of suicidal acts have changed little in the general population. Evidence of reduction of long-term rates of suicidal acts in specific at-risk populations remains very limited, particularly persons with major affective illnesses and other common, primary or comorbid psychiatric and substance use disorders. It is plausible that reduction of psychiatric morbidity should limit suicidal risk, but very little is known about specific effects of most psychiatric treatments or other interventions aimed at suicide prevention. An exception is substantial evidence of lower suicidal risk during long-term lithium treatment that was not equaled with carbamazepine. However, diagnosis and timely therapeutic interventions reach only a minority of psychiatrically ill persons at risk for suicide. CONCLUSIONS Renewed efforts are strongly urged to: (1) improve public and professional awareness of risk factors for suicide, (2) enhance earlier access to appropriate clinical assessment and increasingly safe and effective treatments for affective and psychotic disorders, and (3) encourage and support research to clarify specific benefits and risks of medical treatments and social interventions aimed at preventing suicide.