A small minority of children and adolescents (2-3%) seems prone to suicidality when defined as increased suicidal ideation or behavior during treatment with antidepressants.. Mechanisms proposed to explain emergence of suicidality during antidepressant treatment are : progression of underlying depression reflecting ineffective tre-atmnent, energizing phenomen, activation syndrome and stage shift from depression into mania or mixed state.Future studie of clinical or biological markers may allow a better prediction of which pediatrie patiens are most liable to show behavioral sensitivity to antidepressants.