PURPOSE: To establish non-radioactive assays for detection of antibodies (Abs) to the acetylcholine receptor (AChR) and to muscle specific kinase (MuSK). To show that the assays can be used in Tianjin for testing patients with MG. METHOD: AChR and MuSK Abs in 51 Chinese MG patients' sera were tested in Oxford, UK, using the conventional radioimmunoprecipitation assay (RIPA), a recently described cell-based assay (CBA), and a new non-radioactive fluorescence immunoprecipitation assay (FIPA) which can measure both AChR and MuSK antibodies in one step. 102 MG sera were subsequently tested by CBA and FIPA in Tianjin, China. Based on the different serological subgroups, the clinical features of these 153 MG patients were analyzed. RESULTS: We first confirmed the sensitivity and specificity of the assays in Oxford. There was good agreement between the FIPA and the RIPA for AChR Abs (r² = 0.6; p