The aim of this study was to develop an optimal protocol of processing of rat brain sections permitting to minimize the short-comings of the method of heat retrieval of antigens and preserving its high efficiency. The research was conducted using the methods of heat antigen retrieval, immunohistochemistry and light microscopy. It was shown that prolonged incubation in blocking solution, containing normal serum of an animal - source of secondary antibodies, eliminated false-positive reaction, demonstrated after heat antigen retrieval in paraffin sections of rat brain.