The author introduces the phenomenon of infantile fanaticism through a clinical illustration of a particular group of adult patients met in contemporary psychoanalytic practice - patients that present psychotisation and the strong need for a narcissistic-fanatic object relation. The author bases her work on the theories of Freud, Kohut, Klein, Segal, Bion, Racamier, Abensour, Rosenfeld and others. She refers equally to the findings of Peter Canzler, a German psychoanalyst, who described the psychological mechanism of the formation and functioning of fanaticism with reference to research on fascism. Additionally, she proposes her own theoretical thesis based on her psychoanalytical work. The author alternates between the terms child and infantile, where if mentioned is an adult syndrome, the preference is infantile, while childish (in line with Freudian tradition) is used to describe a desire.