To study the diagnostic characteristics of test systems for detecting antibodies to SARS-Cov-2. We studied the diagnostic characteristics of two test systems for detecting antibodies to SARS-Cov-2, registered in the Russian Federation. The first test system is a kit for detecting total antibodies to SARS-Cov-2 using immunochemiluminescence analysis on the «Cobas e 411» analyzer («Roche Diagnostics», Germany). The second test system is a kit for detecting IgM and IgG to SARS-Cov-2 («Core Technology Co., Ltd», China) by immunochromatographic analysis. The biological material for the study was blood serum. We assessed: diagnostic sensitivity, diagnostic specificity, and predictive value of positive and negative results. In the test system for detecting total antibodies to SARS-CoV-2, using an IHLA, the diagnostic sensitivity and specificity were 100%; the predictive value of positive and negative results was 100%. In the test system for the detection of IgM and IgG to Sars-CoV-2, using IHA, diagnostic sensitivity for IgM and IgG were 100%; diagnostic specificity for IgM - 60%, for IgG - 72%; predictive value of a positive result for IgM - 60%, IgG - 68,18%; predictive value of negative results for IgM and IgG - 100%. The best diagnostic characteristics were found in the test system for the detection of total antibodies to SARS-Cov-2, which must be taken into account when deciding whether to purchase test systems for the detection of antibodies to SARS-Cov-2.