Objective To analyze the clinical characteristics of Duchenne/ Becker muscular dystrophy (DMD/BMD)with the initial presentation of transaminase elevation,in order to improve the clinician's understanding of this disease,and reduce misdiagnosis and missed diagnosis. To investigate the relationship between the elevation of transami-nase and the early stage of DMD/ BMD,and to provide the strategy for early diagnosis. Methods Twenty - four pa-tients admitted to the hospital with elevated serum transaminase as the initial presentation from January 2012 to Decem-ber 2014,who were diagnosed as DMD/ BMD by genetic testing or muscle biopsy,were enrolled. Their clinical data and laboratory examinations were retrospectively analyzed,including clinical features,diagnostic steps,serum muscle en-zymes,genetic analysis,electromyography and muscle pathological changes. Results The 24 patients were all male without family history of DMD/ BMD prior to birth. The average visiting age was (3. 4 ± 1. 2)years (ranging from 0. 8 to 6. 1 years),and 87. 5％ (21 / 24 cases)of cases were preschool children aged 2 - 6 years. Hypertransaminasemia was found in 21 cases (87. 5％)during the kindergarten physical examination,1 case during pre - operative investigation and 2 cases during respiratory infection. Due to its insidious onset,the time interval between incidental finding of elevated transaminase and definitive diagnosis was between 0. 6 and 20. 4 months. Among them,16 cases (66. 7％)had obvious pseudohypertrophy of calf muscles,and 18 cases (81. 8％)showed different degrees of movement disorder,such as unable to jump,easy to fall,and difficulty in climbing stairs. In addition,18. 2％ cases (4 / 22 cases)had a delay in language development. The serum alanine aminotransferase and aspartate aminotransferase levels were 120. 3 - 761. 7 U/ L and 83. 3 - 675. 5 U/ L,respectively. Serum creatine kinase (CK)was found to be markedly elevated (ranging from 3940 to 27510 U/ L)in all patients. Electromyography showed myogenic damage in 13 / 23 cases (56. 5％). DMD gene deletions were found in 18 cases (75. 0％),and duplications in 4 cases (16. 7％). The muscle biopsy performed in 2 cases (8. 3％)multiplex ligation - dependent probe amplification (MLPA)- negative cases showed evidence of dystrophic features on routine histology. Immunohistochemistry showed absent dystrophin staining in all 2 MLPA - nega-tive cases. Conclusion The clinical manifestation of DMD/ BMD is not typical in the early stage,so it is easy to be neglected or misdiagnosed. Elevated ALT and AST are important clues in the early diagnosis of DMD/ BMD. Children with elevated transaminase,in the absence of other signs and symptoms of hepatic injury,may have occult muscular di-sease,most frequently DMD/ BMD. A thorough physical examination and history taking as well as the measurement of serum CK are helpful in the differential diagnosis. Genetic testing or muscle biopsy should be done early for correct diagnosis of DMD/ BMD.