In a patient with fugue states, psychophysiological parameters were studied in the sleep laboratory. Four sleeptalking episodes, which appeared to be fugues without locomotion, were recorded, identical in verbal content to some of the fugues with locomotion that occurred during the diurnal state. The episodes were temporally associated with predormescent and immediate post-rapid eye movement period (REMP) sleep. The case history and laboratory data are presented. An attempt is made to establish a psychophysiological link between fugue states and sleep-dream mechanisms. Differences between REMP and non-rapid eye movement period mentation and their relationship to fugues are discussed.