The authors retrospectively studied histopathologic findings and diagnoses of muscle specimens taken from 188 pediatric patients presenting with clinical neuromuscular disorders in King Chulalongkorn Memorial Hospital between August 1991 and December 2003. Eighty patients (67.8%) established the definite diagnosis by histopathological findings of muscle specimens. About 18.6, 17.7, 7.6, 5.9, 5.0, 3.4, 2.5 and 1.7 percent of the total number of patients were diagnosed as Duchenne muscular dystrophy, spinal muscular atrophy, congenital myopathies, mitochondrial disease, inflammatory myopathies, Becker muscular dystrophy, congenital muscular dystrophy and vacuolar myopathies respectively. Since the histopathological findings in muscle helped to establish the definite diagnosis in most pediatric patients in the present study, thus muscle biopsy is essential for establishing a definite diagnosis in any patient with a suspected neuromuscular disorder.