The ultrasound imaging of quadriceps, gastrocnemius and soleus muscles was performed in 30 patients with Duchenne muscular dystrophy (DMD) and 16 control subjects. In controls, the skeletal muscle itself was scarcely echogenic. However, bone surface and fascia were clearly echogenic. The transverse scan of muscle in all DMD patients showed an increased echogenicity, which made the echo from bone or fascia less intense. The abnormal muscle echo was graded according to Heckmatt et al. From the quantitative aspect, there was a significant correlation between disability scale of DMD patients and abnormal echogenicity of the quadriceps muscle. A similar correlation was also observed between results of manual muscle testing the ultrasound imaging. The soleus muscle was usually less abnormal than the gastrocnemius in the ultrasound imaging. Thus, the ultrasound imaging seemed to provide an important information for the clinical assessment of DMD patients.