Growth rate was assessed in 187 boys affected with Duchenne muscular dystrophy (DMD) and bone age in 127 among them. Patients' heights were compared with their normal sibs, with expected stature according to midparents' stature and with normal Brazilian children of comparable age. The results showed that DMD boys have a normal length and weight at birth, but a delayed growth starting during the first years of life with a mean approximate decrease of -6.00 cm according to the expected height of the normal Brazilian population. The proportion of DMD patients with short stature (below the 3rd centile) was similar in younger boys (up to 7 years) to that in the older group (more than 7 years) of affected boys. Bone maturation in DMD boys did not differ from their normal sibs. Weight was also decreased in DMD patients as compared with normal sibs of comparable age.