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Objectives: Anti‐acetylcholine receptor antibodies (AChR Ab) are one of the pathogenic autoantibodies in myasthenia gravis (MG), and they are specifically mentioned in the Japanese clinical guidelines for MG. In the serological diagnosis and measurement of autoantibodies as an adjunct marker for MG, the radioimmunoassay (RIA) method has been conventionally used as the gold standard. However, there have been several worldwide concerns regarding the use of radioisotopes. In this study, we evaluated the performance of the EUROIMMUN AChR Ab enzyme‐linked immunosorbent assay (ELISA) in comparison with RIA. Methods: ELISA reproducibility and dilution linearity were analyzed using AChR Ab‐positive samples. Sera from 50 patients with suspected MG and 50 healthy donors were used to assess the correlation and qualitative agreement between the two methods. Results: The ELISA showed good interassay precision and dilution linearity. The correlation coefficient, sensitivity, specificity and overall agreement of the ELISA in comparison with the conventional RIA amounted to 0.87, 98%, 92% and 95% (kappa = 0.895), respectively. Analysis of the discordant results suggested that the ELISA might be more capable of detecting low AChR Ab reactivity in patients with suspected MG. Conclusions: The AchR Ab ELISA provides a reliable tool for the quantification of AchR Ab, supporting the diagnosis of MG. As a non‐isotopic assay with good precision, shorter handling time and high correlation with the conventional RIA, the AChR ELISA could be a useful alternative in the laboratory routine. [ABSTRACT FROM AUTHOR]