For some length of time I entertained the idea that paranoia also—or the group of cases belonging to paranoia—is a defense psychosis, that is, like hysteria and obsessions it originates from the repression of painful reminiscences, and that the form of its symptoms is determined by the content of the repression. A special way or mechanism of repression must be peculiar to paranoia perhaps just as in hysteria which brings about the repression by way of conversion into bodily innervation, and perhaps like obsessions in which a substitution is accomplished (displacement along certain associative categories). I observed many cases which seemed to favor this interpretation, but I had not found any which demonstrated it until a few months ago when, through the kindness of Dr. J. Breuer, I subjected to psychoanalysis, with therapeutic aims, an intelligent woman of 32, whom no one will be able to refuse to designate as a chronic paranoiac. I report here some explanations gained in this work, because I have no prospects of studying paranoia except in very isolated examples, and because I think it possible that these observations may instigate a psychiatrist for whom conditions are more favorable, to give due justice to the moment of defense in the present animated discussion on the nature and psychic mechanism of paranoia. It is of course far from my thoughts to wish to show from the following single observation anything but that this case is a defense psychosis, and that in the group of “paranoia” there may be still others of a similar nature.