In psychiatry the interplay of sameness and otherness is of special interest and importance. Patients suffering from mental disorders are deeply affected by the experience of the otherness of oneself and the resulting marked changes in the surrounding world. Otherness is strongly connected with alienation, again a phenomenon which most of our patients with mental disorders suffer from. In this context we should not forget, however, that in former times medical doctors dealing professionally with mental disorders were called alienists indicating on the one hand that they are treating ‘aliens’ but on the other hand indicating the ‘alien role’ of psychiatrists. Alienation leads quite often to objections and hostile behaviour. For these reasons hospitality has to play a profound role in treatment programs for patients suffering from mental disorders and their aftermaths. J.Derrida rightly underlined the structural similarity of the words hostility and hospitality. Treatment settings are usually characterized by mutual and ambiguous relations between sameness and otherness, between acceptance and rejection, welcoming and refusal, integration and disintegration. This means that the problems resulting from the interplay of the sameness and otherness do not affect only patents but also treatment teams. One of the way-outs of the dilemma may be a profound change in treating persons with mental disorders - from the monologue of professionals to the mentally ill patients (no seldom leading to the experience of alienation) to a professional dialogue in a warm atmosphere of hospitality opening the chance for a concerted treatment approach based on reciprocity and confidence.