Myopathy may be associated with very variable cardiac involvement, the expression of which is related to the type of neuromuscular disease and also to the individual. This retrospective study, performed between 1986 and 1991, was undertaken to determine the prevalence of cardiac involvement in myopathy. A total of 216 subjects with an average age of 34 years were reviewed by clinical examination, ECG, echocardiography and Holter ECG monitoring. Some patients also underwent complementary radionuclide (scintigraphy, angiography) and electrophysiological investigations. The results confirmed cardiac disease in over a half of patients. Although 3/4 of the patients were asymptomatic from the cardiac point of view at the time of evaluation, the severity of certain lesions led to a number of specific therapeutic interventions. This suggests that simple, non-invasive cardiac diagnostic procedures should be undertaken systematically in the early stages of myopathic disease.