The infectious allergy plays an important role in the pathogenesis of brucellosis. In the allergy diagnostic of toxoplasmosis the cell reactions in vivo are equally applied with the Burnet intradermal allergic test. In the present study the reaction of leukolysis was applied to detect the sensibilization of leucocytes in blood and saliva under brucellosis. The reaction is considered positive in case of occurrence of lysis of 15% and more of leucocytes after incubation with allergen. The percentage of lyzed leucocytes of blood and saliva makes 18.4 +/- 1.2 in case with brucellin, 16.8 +/- 0.75 in case of acute brucellosis and 26.6 +/- 1.12 in case of chronic brucellosis and 28.9 +/- 1.4 in case of negative results of reaction of leukolysis with control antigens (toxoplasmin and medium 199). The reaction of leukolysis can be applied in allergy diagnostic of brucellosis due to its higher informativity with leucocytes of blood and saliva.