A thorough histological description of 17 patients with congenital muscular dystrophy (CMD) is presented. The biopsies were performed in the left superficial deltoid muscle and processed with histochemical techniques. All samples showed connective tissue proliferation, changes in the internal architecture, necrosis, increase of adipose tissue, ma-crophagia, fiber regeneration and segmentation, central nuclei, and type I fiber predominance. The histological hallmarks of this entity are the marked endomysial connective tissue proliferation that frames one fiber from the other, and the important changes in the fiber's internal architecture. Those two abnormalities are extremely helpful to differentiate, on histological grounds, CMD from limb girdle muscular dystrophy and Duchenne/Becker muscular dystrophy. CMD presents a particular natural course and should be individualized apart from other muscular dystrophies.