BackgroundThe seroprevalence rate of human T‐lymphotropic virus I and II (HTLV‐I/II) in Korean blood donors has been known as 0.004%, and HTLV‐I/II Ab screening test has been performed since 2008 in Korea. Korea Ministry of Food and Drug Safety (MFDS) approved two chemiluminescent microparticle immunoassays (CMIA) for testing HTLV‐I/II antibody, ABBOTT PRISM HTLV‐I/HTLV‐II and ARCHITECT rHTLV‐I/II. A multicenter performance evaluation study in Europe and Japan was carried out with the new electrochemiluminescence immunoassay (ECLIA) for HTLV‐I/II antibody detection, Elecsys HTLV‐I/II assay which launched in 2017, but not in Korea. We aimed to evaluate the clinical performance of Elecsys HTLV‐I/II assay in comparison with ARCHITECT rHTLV‐I/II for the detection of HTLV‐I/II antibody with Korean samples.MethodsFor sensitivity evaluation, 100 HTLV‐I/II‐positive Korean standards from Korean Red Cross and two HTLV‐II‐positive samples that were purchased from Seracure were used. For the specificity, 500 potential donor specimens from Korea University Hospital healthcare center were used. All the samples were simultaneously analyzed by the two HTLV‐I/II assays, Elecsys HTLV‐I/II assay and ARCHITECT rHTLV‐I/II assay.ResultsElecsys HTLV‐I/II assay and ARCHITECT rHTLV‐I/II assay showed a complete agrement. Elecsys HTLV‐I/II assay showed 100% sensitivity (95% CI: 96.38‐100.0) and specificity (95% CI: 99.26‐100.0).ConclusionsElecsys HTLV‐I/II assay is as reliable as ARCHITECT rTHLV‐I/II assay, and can be used as a screening test for HTLV‐I/II in Korea.