The surface antigen has been obtained from C. jejuni culture and its immunochemical analysis has been carried out by the methods of immunoelectrophoresis, double diffusion with homologous and heterologous rabbit sera. The protein profile of this antigen has been studied by means of vertical electrophoresis in polyacrylamide gel with sodium dodecyl sulfate, and the molecular weight of the protein components of the antigen has been determined. The presence of anti-Campylobacter antibodies has been revealed in a number of rabbit sera by enzyme immunoassay techniques. The results thus obtained indicate the possibility of developing the enzyme immunoassay for the determination of antibodies in the sera of patients with Campylobacter infection.