Much progress has been made over the last few years in understanding and classifying neuromuscular diseases. The heart is frequently affected but often in a dissociated manner with respect to the neuromuscular signs although it has a significant impact on the prognosis. In children and adolescents, the dystrophinopathies, especially Duchenne's muscular dystrophy, are the principal problems but the mild arrhythmic events observed seem to be related to left ventricular dysfunction. On the other hand, in myotonic dystrophies (Steinert's disease), ventricular arrhythmias or conduction defects may appear at an early stage of the disease with serious consequences justifying appropriate follow-up and invasive preventive measures. Emery Dreifuss X-linked dystrophy and other laminopathies are rare conditions but are associated with sudden death and cardiomyopathies of the young adult. Specialised cardiological follow-up is justified in childhood from the time of diagnosis. Medication or implantable electric devices may be justified before the end of the second decade of life. Progressive infra-hisian conduction defects have also been reported in Kearns-Sayre oculo-pharyngeal myopathy. Prospective studies are required at this age to determine the natural history of these pathologies that are probably under diagnosed. The present recommendations, which are based mainly on data from adult series, could then be adapted for younger patients.