Muscle ultrasound scanning is a non-invasive and painless technique for evaluating muscle disorders in childhood. We have performed ultrasound scans of the quadriceps muscle in 26 children with various forms of congenital muscular dystrophies. There were 8 patients clearly showing selective involvement within the components of the quadriceps. In all cases showing selective involvement, the rectus femoris was spared and the vastus muscles were the affected group. Our findings support the concept of heterogeneity, often encountered in congenital muscular dystrophies.