The range of psycho-pathological conditions for which the term “fugue” has been used has increased considerably and is still increasing. Originally the term was chosen to denote transitory abnormal behaviour characterized by aimless wandering and more or less marked alteration of consciousness, usually but not necessarily followed by amnesia. At present it is used for a variety of different symptoms, some of which have little in common; the psychiatrist using the term has to define what kind of fugue he means if he wishes to avoid misunderstanding and confusion. The reasons for the great popularity of the term are manifold. It is short, handy, vague, and has even a distinguished foreign flavour. But there are other reasons apart from those virtues. When the psychological mechanisms underlying abnormal behaviour were first studied two were regarded as responsible for the origin of fugues: dissociation and escape. From that time dates the tendency to describe as fugue nearly every condition of transitory alteration of consciousness which can be understood as the result of those mechanisms. Thus a remarkable change of conception has taken place; while the term “fugue” originally described a certain type of abnormalbehaviourcharacterized by running away and wandering under a strong impulse and associated with clouding or narrowing of consciousness, it later came to be used, in addition, as the description of various results of the psychologicalmechanism of escape, without regard for the resulting behaviour. Obviously the fact that fugue means escape invited that change of conception. Considering the grèat number of neurotic and psychotic symptoms in the origin of which the two mechanisms mentioned above are supposed to play a part, there are hardly any limits to the use of the term. It is not intended to survey the whole literature on what has been called fugues; a few instances from current text-books and recent articles will demonstrate for how many conditions the term has been used in recent years.