The severity of depression is related to its clinical features and also its impact in terms of morbidity and mortality. Depression is the most common psychiatric disorders associated with suicide and is found in almost one out of two cases, in 85% of situations associated with another mental disorder. Clinically severe depression also has a 4 to 5 times higher long term risk of suicide than mild or moderate depression. Severe depression is also associated with significantly increased deaths from natural causes : in absolute terms this is similar to the additional mortality rate from suicide. Cardiovascular diseases, particularly coronary, are a particular feature of this increased cause of natural deaths. These findings justify the development of prevention and screening for these diseases in depressed patients.