The term paranoid is derived from the Greek word paranoia meaning nadnese. It does not only mean self-reference, but there are various personality features as they are hostility, a tendency towards aggressiveness, irritability, a lack of sense of humour, feelings of overestimation of one-self and a tendency towards accusations. These features may appear also within normal psychology and they becomeclinically important after thein increase of intensity and conspicuousness (los sof hearing, long-term abuse of alcohol and psychostimulants) and organic disorders of the brain may contribute to the development of paranoidity. A mechanism of projection is considered as a decivise factor from the point of view of dynamic psychiatry. Clinically unimportant sign sof paranoidity can be observed due to unusual situations. If a paranoid reaction becomes more serious, formation of a paranoid delusion should be taken to account. In our koncept the term paranoid and paranoidity should be used only as a psychopathological term.

        Key words: paranoid syndrome, development of paranoia, biological cause of paranoidity, mechanism of projection, formation of delusion, paranoid disorders in ICD-10.