Most suicides have a diagnosable psychiatric disorder, most frequently, a mood disorder. Psychosocial issues and neurobiological abnormalities such as dysregulation in stress response systems contribute to suicidal behavior. All psychiatric patients need to be screened for the presence of suicidal ideation. Clinicians are expected to gather information about patient's clinical features and to formulate decisions about patient's dangerousness to self and the treatment plan. As psychiatric disorders are a major risk factor for suicide their pharmacologic and psychological treatment is of utmost importance to prevent suicide. Restriction of access to lethal means is important for suicide prevention.