BACKGROUND: Hepatitis B virus (HBV) infection is the leading cause of liver disease in Korea and, is usually diagnosed with serologic testings. The automated immunoassay analyzer, Roche Modular Analytics E170 (Roche Diagnostics, Mannheim, Germany; E170) tests HBV serologic markers based on electrochemiluminescence (ECL) method. We would like to evaluate analytical performances of E170 for HBV serologic markers. METHODS: We evaluated the precision of E170 for 6 serologic markers (HBsAg, anti-HBs, HBeAg, anti-HBe, IgG anti-HBc, IgM anti-HBc) with positive pooled serum. A comparison study with the AxSym immuoassay analyzer (Abbott Laboratories, Abbott Park, IL USA) was performed using patient's sera. HBsAg confirm test was evaluated using the specimens with cutoff index (COI) between 1 and 10 for HBsAg. RESULTS: The total coefficients of variations were below 5% for all of the 6 serologic markers. Method comparisons between E170 and AxSYM showed a good concordance rate; the rates of positive and negative agreements were more than 90% for almost all the serologic markers. HBsAg confirm tests for 84 samples with COI between 1 and 10 revealed that only 36 samples (43%) were true positive for HBsAg. Among 36 true positive samples, 9 samples (25%) were anti-HBs positive concurrently, but these showed low antibody titer (<50 IU/L). CONCLUSIONS: The E170 showed good precision for all HBV serologic markers and a high concordance rate with the AxSYM. Therefore, E170 can be used as a routine immunoassay analyzer for the testing of HBV serologic markers. In addition, HBsAg confirmatory test might be useful to confirm the true positivity when a specimen has low cut-off index (1-10).