"Folie du doute" related to obsessive disorders manifests with doubts about managing habitual actions, reality of what is happening and existence of surrounding subjects; ruminations, indecision emerged as incapability to choose a definite behavior line. Sixty-six patients, 27 men and 39 women (mean age 31.3 years) have been examined. Three clinical "folie du doute" variants were distinguished: "repeated control" obsessions (doubts are realized by re-control of the actions committed); obsessive doubts defined by contrastive ideas of expedience for choosing the approach contrastive to the taken decision; anxious ruminations (lack of assurance in the past actions and obsessive doubts of the variants supposed-to-be). "Folie du doute" emerged in different psychic disorders, the first variant manifesting in the scope of neurotic-like schizophrenia; the second one--in psychogenic states or psychogenically-provoked exacerbations of psychopathic-like schizophrenia; the third one being regarded in the structure of cyclothymiac's depressive phases. In the clinical contest, "folie du doute" manifestation proves to be unfavorable prognostic marker.