目的　探讨线粒体脑肌病伴高乳酸血症和卒中样发作综合征(MELAS)的诊断与治疗。方法　回顾性分析2例MELAS患儿的临床特征及诊疗过程。结果　2例患儿主要临床表现为卒中样发作、抽搐、视物模糊、高乳酸血症；发作期头颅磁共振成像结果符合典型的MELAS综合征影像学表现；基因测序存在mtDNA的A3243G点突变；改善供能及皮质激素治疗后症状明显改善。结论　MELAS临床症状复杂多样，血乳酸及头颅磁共振成像检查有助临床诊断，确诊需要肌肉活检或基因检测，皮质激素治疗有效。

Objective　To discuss the clinical features, diagnosis and treatment of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome in children. Methods  The clinical features and treatment process of two children with MELAS were retrospectively analyzed. Results　The main clinical features of MELAS were stroke-like episodes, seizure, visual anomaly and lactic acidosis. Cephalic MRI findings performed during episode periods were in accord with the typical radiographic features of MELAS. Gene testing on the two children and their mothers showed the point mutation of A3243G in mitochondrial genome. The symptoms were improved significantly after energy supply and corticosteroid treatment. Conclusions  MELAS syndrome is easy to be misdiagnosed due to the varied clinical features. The diagnosis depends on the musclebiopsy and gene testing. Corticosteroid therapy is effective for MELAS syndrome.