Seven patients with the Frégoli syndrome were described. These patients were studied clinically and by routine laboratory tests, electroencephalograms (standard and sleep recordings, sphenoidal electrodes), echoencephalograms, air-encephalograms, brain scanning, and psychological methods (Wechsler, Rey and Benton tests). The following basic conclusions were drawn: All patients were psychotic and in most cases schizophrenia constituted the nosological setting in which the Frégoli syndrome developed. The paranoid element was marked in all cases. All patients were single, young and, with one exception, male. Clinical evidence as well as electroencephalographic, air-ence-phalographic, echoencephalographic, and psychological findings suggest that a strong organic component contributes to the patho-genesis of the Frégoli syndrome.