Different immunohistochemical techniques have been employed to identify the anti-neuronal antibodies in patients with paraneoplastic neurological syndromes. The finding of anti-neuronal-specific autoantibodies in serum or cerebrospinal fluid well correlates with particular types of tumors, thus leading, in many cases, to an early cancer identification. In this work, we have compared three immunohistochemical methods (immunofluorescence, indirect immunoperoxidase and avidin-biotin immunoperoxidase) on frozen and paraffin-embedded sections of rat cerebellum in order to set up a reliable and simple technique for the diagnosis of these syndromes. Our study demonstrates that the best result was obtained by using frozen sections of rat cerebellum and the avidin-biotin immunoperoxidase method that also allowed the identification of anti-GAD antibodies not detected in paraffin-embedded tissues.