About 1500 samples of serum and cerebrospinal fluid were screened by the methods of indirect immunofluorescence and immunohistochemistry and 5 patients were found with positive specific antineuronal IgG antibodies described as anti-Yo, confirming the paraneoplastic origin of the neuro- logical syndrome. From the oncological point of view ovarian cancer was diagnosed in four cases and in one case only metastatic disease of liver was present without a known primary tumour. In some cases the neurological paraneoplastic syndrome is diagnosed before the cancer is detected and the clinical course of the disease is usually severe without response to treatment. The importance of early diagnosis is based on potentially effective treatment of the tumour often localized „in situ“ and on the differential diagnosis of cerebellar syndrome.

        Key words: paraneoplastic cerebellar syndrome, anti-Yo antibodies, immunofluorescence