We report an isolated case of a girl aged three years six months with Duchenne muscular dystrophy. Analysis of the patient's DNA with a probe covering the DNA gene revealed no deletion. Dystrophin, studied in biopsied muscle from the patient, using antidystrophin antibody in combination with immunofluorescence, was nearly completely absent. In this sporadic case of female muscular dystrophy, the identification of dystrophin-deficient muscle fibers made it possible to establish an accurate diagnosis of DMD affected female.