Abstract: Objective: To explore the clinical,electrophysiological and pathological characteristics of myotonic dystrophy(DM).Methods: The clinical,electrophysiological and pathological data of 8 patients with DM were retrospectively analyzed.Results: The different degree of muscle weakness,myotonia or amyotrophy symptoms in 8 cases were found.The alopecia,intelligence disorder,menstrual disorder of no skeletal muscle symptoms were found in part of the patients.No family history in 3 cases and myotonic potential diagnosed by electromyogram examination in 7 cases were identified.Under the light microscopy,the unequal muscle fibers in size,nucleus moving inward,muscle membrane nuclear increasing,nucleus gathering and nuclear chain forming were found.The sarcoplasmic masses in 1 case and muscular dystrophy diagnosed by NADH-TR staining in 7 cases,which included that the major muscle fiber atrophy in 5 cases were type Ⅰ fiber,were identified.Conclusions: Electromyography and skeletal muscle biopsy have important value in diagnosing myotonic dystrophy.The illness onset,and skeletal muscle and multi-system involvement features can benefit for the DM typing.The illusion of "no family history of genetic" caused by genetic anticipation of myotonic dystrophy should be paid attention to.