[Becker's benign muscular dystrophy. Observations on 1 family]

Three males in a family had Becker's benign muscular dystrophy. In addition, there were five likely female carriers, three of whom presented altered biochemical findings. Agreement is expressed with the view of other workers that Becker's form can be distinguished from the serious form of the disease on the grounds of exclusive expression in males, late onset of the first symptoms, recessive transmission linked to the X chromosome, extremely slow progression, and long survival.