Objective To investigate the value of the immunohistochemistry and Western blot in the diagnosis of the benign muscular dystrophy with abnormal dystrophin expression.Methods The medical histories and clinical manifestations of 4 patients were collected.In addition to routine histological and histochemical studies,expression of dystrophin in muscle fibets was observed by immunohistochemical reaction(dys-N,dys-R and dys-C)and Western blot to anti-dystrophin antibody.Results Two patients had muscular weakness while another 2 patients had only muscular pain and elevated creatine kinase blood levels without muscular weakness.Histochemical stains showed atrophy,hypertrophy and fiber splitting in 2 patients,while only variation in fiber size was presented in anothor 2 patients.One patient had no reaction for dys-N,but had immunostains for dys-C and dys-R in the sarcolemma of muscle fibers.Western blot confirmed that the band of dys-C and dys-R was partly deficient,and the band of dys-N was absent compared with control.Three patients had no reaction for dys-R,but had immunostains for dys-C and dys-N.Compared with control,Western blot confirmed that the band of dys-R was absent,and the band of dys-C and dys-N were truncated.Conclusion The immunohistochemistry is stained with three anti-dystrophin antibodies to avoid diagnostic errors.Western blot is essential to further determine the type of dystrophin protein.