The histochemical and immunocytochemical findings of biopsied muscle in a 2-year-old girl with Marinesco-Sjögren syndrome are reported. Muscle histology consisted of mild muscular dystrophy, such as that found in limb-girdle or non-Fukuyama congenital muscular dystrophy. By immunocytochemical stain using anti-dystrophin antibody, Duchenne and Becker muscular dystrophies were excluded. In addition to characteristic clinical features, including ataxia, congenital cataract, and psychomotor retardation, muscle involvement is essential to the diagnosis of Marinesco-Sjögren syndrome.