Paraneoplastic neurological syndromes (PNNS) are neurological disorders due to autoimmune attack on the nervous system, induced by a tumor remote from these structures. The existence of relatively stable associations between the neurological syndrome, the type of antineuronal antibodies (Ab) and the nature of tumor has been proven. At the same time, there are no pathognomonic combinations of this kind: the same antibodies can be detected in diff erent types of tumors and in diff erent syndromes. In addition, level of reliability of the diagnosis of PNNS is considered, taking into account the phenotype of the neurological disorder, the presence of certain antibodies in the blood serum, the verifi cation of oncopathology and the duration of the observation for the patient.