The institutional psychiatric treatment of migrant workers is difficult. But it is also necessary: the most dangerous evolutions happen when there is no intervention or during long breaks of therapy. From their own experience, authors ask themselves about what, in usual attitudes of psychiatrist, can drive into blind-alleys. The symptomatology shown by maghrebian migrant has implications in fields of sociology, culture and psychology, with wide extensions in politics, economics, etc. In front of symptoms (described there), different persons give different institutional answers, described too. Each pathological situation is either revelating of migrant's contradictions or origin of new contradictions.