This chapter discusses two types of paramnesia: déjà vu and jamais vu with a focus on their clinical features. The cause of déjà vu has been associated with anxiety, dissociative mechanisms, mood and personality disorders, schizophrenia and organic brain syndromes. In non-psychopathological conditions, predisposing factors include emotional trauma, exhaustion, psychomimetic drugs, fatigue, severe stress, hyperventilation syndrome and illness. As to psychopathogenesis, many authors have viewed déjà vu experiences primarily as a disturbance of memory. Psychoanalytically oriented authors regard the jamais vu experience as a defence mechanism 'by which an event is torn out of the context of experience, removed from consciousness, and rigidly warded off'. Both déjà vu and jamais vu were considered as memory disorders but currently other hypotheses are being entertained, for example, these states are considered in DSM IV as being related to dissociation.