AIM:To study the electromyogram and muscular pathological features of adult sp inal muscular atrophy(SMA4).METHODS:46 cases of SMA4 were evaluated based on cli nical,histopathology,enzyme histochemistry and ultrastructure.RESULTS:A mean age of the patients with SMA4 was 38.7 years,clinical progressed was slowly.Clinic manifestations mainly appeared proximal muscular weakness and progressive muscul ar atrophy,and there was a relatively good prognosis.Laboratory found:one-fourt h of the disease had elevated serum creatine kinase levels.Eletromyogram reveale d neurogenic damages. The muscular pathological changes showed small groups of a trophy of denervation,ATPase reaction showed fibre-type grouping of renervation and hypertrophy in muscle fibers.CONCLUSION:Muscle biopsy was important;it coul d to help to establish to diagnose the disorder and provided available cases for gene study. AIM: To study the electromyogram and muscular pathological features of adult sp in al muscular atrophy (SMA4). METHODS: 46 cases of SMA4 were evaluated based on cli nical, histopathology, enzyme histochemistry and ultrastructure .RESULTS: A mean age of the patients with SMA4 was 38.7 years, clinical progressed was slowly. Clinic manifestations middle had proximal muscular weakness and progressive muscul ar atrophy, and there was a relatively good prognosis. Laboratory study: one-fourt h of the disease had elevated serum creatine kinase levels. Eletromyogram reveale d The muscular pathological changes showed small groups of a trophy of denervation, ATPase reaction showed fiber-type grouping of renervation and hypertrophy in muscle fibers. CONCLUSION: Muscle biopsy was important; it coul d to help to establish to diagnose the disorder and provided available cases for gene study.