The aim of the study was to compare the prevalence of predefined ECG abnormalities, compiled from the literature, and of increased electrocardiographic myopathy indices (QT/PQs, P/PQs, R/S) among myopathy patients, patients with coronary heart disease and healthy subjects. ECGs from 27 myopathy patients, 35 patients with coronary heart disease and 36 healthy subjects were investigated. ECG abnormalities most often observed in myopathy patients were ST-abnormalities, T-wave abnormalities and tall R and/or S-waves. At least one increased electrocardiographic myopathy index was observed in 19% of the myopathy patients, 20% of the patients with coronary heart disease and 19% of the healthy subjects. At least one predefined ECG abnormality was found in 78% of the myopathy patients, 86% of the patients with coronary heart disease and 33% of the healthy subjects. In conclusion, ECG abnormalities frequently occur in myopathy patients and nearly as often as in patients with coronary heart disease. Electrocardiographic myopathy indices lack specificity and are thus of minor help in assessing myocardial alterations in myopathy patients.