Muscle spindles have been studied in 7 autopsied cases of Duchenne muscular dystrophy. The autopsies of 2 boys of similar age who died without known neuromuscular disease were used as controls. The abnormalities found consisted of degenerative changes, atrophy and loss of intrafusal muscle fibres, thickening of the spindle capsule and widening of the periaxial space. In some very severely affected muscles there was evidence that spindles were destroyed in the course of the disease. Statistical comparison of these observations was made between the pathological and normal material. The muscle spindle innervation appeared normal in sectioned material. Teased preparations were not available for study.