The clinical and electrocardiographic findings of 82 patients presenting with hypertrophic cardiomyopathy were compared with the distribution and extent of myocardial hypertrophy. The clinical and ECG signs did not depend on either the presence or the degree of the obstruction. Subjective complaints (with the exception of dypnoea) were not related to the value of myocardial thickness but they correlated with the square extent of the area affected by hypertrophy of the myocardium. It was distinct in the case of dyspnoea and especially syncope the occurrence of which was significantly higher in patients with a higher extent of hypertrophy. This extent of hypertrophy was reflected in our previously published classification of hypertrophic cardiomyopathies which is based on echocardiographic analyses of the individual parts of myocardial thickness.