The aim of investigations was to determine the stability of ELISA components preserved under different conditions. The following components for the ELISA were used: the secreted/excreted antigen prepared from H. bovis L1 larvae, its fraction containing hypodermine A, conjugat, positive and negative control sera. Freezing at -20 degrees C, lyophilization and preservation at 4 degrees C were applied. Seven kits for the ELISA containing components preserved using described methods, were prepared. The identical packets of sera were examined by the ELISA directly after preparation of the kits (day '0'), and next, at 3-4 week intervals for 9 months. The experiments showed that the best method of conservation of ELISA components for the detection of H. bovis antibodies was lyophilization. The kits prepared in this way did not lose their characteristics for 9 months and their specificity and sensitivity were close 100%.