One foreign and two Russian recombinant enzyme immunoassay test-systems were comparatively investigated under conditions of an encoded experiment. Sensitivity in the experiment with the Russian test-systems Borreliosis-ELISA-IgG and Lyme Best was 63.8 and 68.8% respectively. As for the test-system Borrelia IgG Recombinant, it was 47.5%. All the test-systems were highly specific (94.4 to 99.5%). The test-systems Lyme Best and Borrelia IgG Recombinant revealed partial cross reactions with sera from patients with systemic lupus erythematosus and leptospirosis.