Forty patients with idiopathic hypertrophic subaortic stenosis have been studied. It was established that these patients had early signs of cardiac insufficiency (cardiac palpitations, fainting fits, dyspnoea) as a result of morphological changes in the myocardium (micro- and macrofocal cardiosclerosis). With the aid of contrast methods of investigation and phonography it was shown that in microfocal cardiosclerosis the index of the systolic murmur varies from 0.5 to 3, the planimetric index from 0.8 to 1.0. In macrofocal cardiosclerosis from 1.5 to 0 and less than 0.8, respectively.