In the vast majority of cases, the prognosis for depression is good. Of course, this is true only when someone is in treatment for depression. Untreated depression usually doesn't go away by itself, and often gets worse with time. And remember, untreated depression can be terminal, since it is the leading cause, by far, of suicide. Depression is a very serious illness which demands treatment--but those who take the difficult step of getting treated for it, will usually recover.