Suicide in the mental hospital is first a human tragedy that affects the patients' families and relatives but also touches all medical staff involved. As for suicide prevention, it is a key issue of public health, and the canton of Vaud has made it a top priority of his mental health policy. We will present some epidemiologic data general of suicide and some specific elements to our institution, the Psychiatry Department of the Centre Hospitalier Universitaire Vaudois (DP-CHUV). Then we will show how our institution addresses the issue of suicide prevention through the analysis of so-called « adverse clinical events » and the systematic training of its caregivers.