Schwartz-Jampel syndrome (SJS) is a disorder characterized by myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation. We present two boys of ages 4 and 8 years with SJS. Their clinical, electromyographic and histopathological findings were similar to those described, except for computed tomography (CT) images that revealed diffuse high attenuation in sternocleidomastoid muscles and low attenuation in the paraspinal, quadriceps, sartorius, soleus and gastrocnemius muscles. This is the first report describing abnormal muscle CT findings associated with SJS. Additional studies of muscle CT might help to improve understanding of the pathogenesis of SJS.