1846 samples of serum and cerebrospinal fluid drawn from neurological patients suspicious of parane- oplastic disease from the Czech Republic were investigated. Various types of paraneoplastic autoanti- bodies were detected by the method of indirect immunofluorescence. In the group of 4 patients specific paraneoplastic antineuronal IgG antibodies called anti-Hu (ANNA-1) were found. These immunofluo- rescent findings were confirmed by immunohistochemistry and Western blot. These laboratory findings were associated with the clinical syndrome of encephalomyelitis/sensory neuropathy. From the onco- logical point of view small cell lung cancer was diagnosed in 3 cases and in 1 case low differentiated prostate cancer. The clinical course of the disease was severe in 3 cases, 1 patient was clinically non-progressive. The importance of early diagnosis is due to the possibility of effective treatment of tumours, as in the case of the patient with prostate cancer „in situ“ with subsequent oncological remission and in the differential diagnosis of encephalomyelitis/sensory neuropathy syndrome. Pati- ents with advanced small cell lung cancer died because of progression of oncological disease with advanced paraneoplastic neurological syndrome.

        Key words: paraneoplastic encephalomyelitis/sensory neuropathy, anti-Hu (ANNA-1) antibodies, im-