Three patients with Duchenne muscular dystrophy presenting with failure to thrive in infancy are described. Their families noted poor growth and sought medical advice up to six months before the diagnosis was suspected. Growth charts showed weight loss between 4 and 18 months of age. Length growth was affected while growth in head circumference remained unaffected. No causes of failure to thrive were found at presentation. Failure to thrive in Duchenne muscular dystrophy has been described previously but it is neither widely recognised nor understood. Poor growth in the first years and eventual short stature, however, is a well described feature of Duchenne muscular dystrophy. Failure to thrive in our three patients may be an extreme manifestation of this.