Abstract The name of G. de Clerambault is nowadays used to designate two distinct psychiatric syndromes: in France and in Russia, the “mental automatism”; in USA and Great Britain, the erotomanic delusion. The mental automatism becomes Clerambault's syndrome at the congress of French alienists of Blois (1927), by the proposition of Angelo Hesnard. The denomination is adopted by Eugen Minkowski in 1933, whereas Clerambault is still alive. The “great automatism” includes the “first rank symptoms” of the schizophrenia described by Kurt Schneider (1939). The symptoms of the “little automatism” are near from the schizophrenic thought disorders of Bleuler (De Morsier, 1929; Heuyer, 1950). Better than the theory of John Hughlings Jackson, they foreshadow the dichotomy between positive and negative symptoms in the schizophrenia (Berrios). The divergences with the “organo-dynamic” theory of Henri Claude and of his pupil Henri Ey (1934, 1948) are more about the psychopathology of the hallucinations, in relation to the delusion, than about the organic origin of the syndrome. “Pure” erotomanic delusion is discussed by Capgras (1923) and then by the pupils of Henri Claude (Lacan, 1932, Ferdière, 1937). It is named Clerambault's syndrome 20years later in the American textbooks of psychiatry (Arieti, 1959; Lehman, 1967). Its comorbidity with several other psychiatric disorders is described in many papers. An “erotomanic type” of the delusional disorder is isolated in the DSM-III-R. After their quarrel of 193l, Jacques Lacan makes a “return to Clerambault” in the years following the 2nd World War and presents him as his “only master in psychiatry” (1966). Many influential French psychiatrists (Guiraud, Heuyer, Daumezon, Baruk, Sivadon) present him as a pionneer. At the end of the 20th century, a biography and a film are exclusively devoted to him.