Objective To investigate the clinical and pathological features of skeletal muscles in patients with limb-girdle type mitochondrial myopathy in one family.Methods The clinical data of three patients within a family with progressive muscular weakness as the major feature were collected, and the results of muscle biopsy were analyzed. Mitochondrial gene detection was performed for all family members.Results In this family, the age of onset ranged from 30 to 47 years, and the major manifestations were muscle weakness and reduced exercise tolerance in trunk muscles and proximal extremities, as well as the involvement of respiratory muscles in the advanced stage. Laboratory examination revealed mildly elevated serum creatine kinase and increased blood lactic acid, and electrophysiological results showed myogenic damage. The pathological examination of skeletal muscles showed that all the three patients had typical ragged red fibers (RRFs); with the prolonged course of the disease (2, 4, and 14 years, respectively), muscle weakness became more severe and there were more RRFs (5%, 10%, and 30%, respectively). Cytochrome C oxidase staining showed that most RRFs were hyperchromatic, while there were negative RRFs. No strongly succinate dehydrogenase-reactive blood vessels were detected by succinodehydrogenase staining. Gene detection found the presence of mtDNA A3243G mutation in this family.Conclusions In the patients with limb-girdle type mitochondrial myopathy, the muscle groups in the trunk and proximal extremities are involved selectively, and the number of RRFs in the skeletal muscles is positively correlated with the progression of the disease.