The aim of these investigations was to prepare the antigen and control sera for the ELISA. Positive control sera were obtained from 163 cows showing clinical symptoms of H. bovis infection and negative control sera from 60 cows free from the infection. The antigen for the ELISA was obtained from H. bovis L1 larvae. Three basic fraction were isolated from whole excreted/secreted antigen by elution from gel and by preparative isoelectrofocusing. Using the Western-Blotting method it was demonstrated that Hy A (22-24 kDa and pI 4-5) had the best antigenic property. As can be seen from these investigations the developed ELISA kit for the detection of H. bovis antibodies in cows is highly specific and sensitive.