1. Part I. A comparative analysis of the electrocardiograms, teleoroentgenograms, and kinetocardiograms (ultralow-frequency precordial movements) was made in two groups of patients: 60 patients with arterial diastolic hypertension, and 55 patients with acquired aortic valvular disease. Kinetocardiography demonstrated the highest percentage of abnormalities (87 per cent) when compared to the other techniques. The kinetocardiogram, although more frequently abnormal than the teleoroentgenogram or electrocardiogram, probably reflects different aspects of left ventricular function. Because of the uncertainty as to the exact mechanism and factors which produce the exaggerated and prolonged impulse in acquired left ventricular heart disease, the abnormality of the left ventricle as manifested by a prolonged “thrust” is probably best referred to as left ventricular overload. 2. Part II. The normal left ventricular impulse is defined as a localized outward movement, usually near the mid-clavicular line in the fifth intercostal space. It usually begins about 0.08 second after the onset of the QRS complex in the electrocardiogram, shortly after left ventricular ejection begins. The left ventricular thrust in left ventricular overload is often increased, and the variations encountered are described. Certain features are presented which differentiate the thrust from right ventricular movement due to increased function or hypertrophy of the right ventricle. 3. Part III. Kinetocardiographic traces from 102 patients with acute and old myocardial infarctions were studied, and the data are compared with findings in groups of patients with arterial diastolic hypertension, acquired aortic valvular disease, and mitral stenosis. The bulge is defined as any paradoxical systolic outward movement which begins early in the course of systole and has a duration of 0.20 second or more above the base line. Sixty-eight per cent of the patients with myocardial infarctions were found to have bulges in one or more precordial or epigastric areas. The incidence of bulges in patients with anterior infarctions was 72 per cent, but only 62 per cent in patients with posterior infarctions. The location of the maximum bulge was important in distinguishing the paradoxical movements from other types of impulses, such as those due to left ventricular overload. It was noted that in 17 per cent of the patients with infarction the maximum impulse was located in the K 2 position, in 35 per cent in the K 3 position, and in 52 per cent in either the K 2 or K 3 position. Moreover, in 17 per cent of the patients the maximum impulse was in the epigastric area. Thus, in a total of 69 per cent of the patients the maximum paradoxical impulse was in an area which is an uncommon location for the largest impulse (PMI) due to left ventricular overload. Nevertheless, in approximately 31 per cent of the patients with infarctions the maximum impulse was at the K 4 or K 5 area, and these impulses could not be distinguished from those due to left ventricular overload by mere inspection of the trace or by palpation. Although the kinetocardiogram cannot be used as the sole criterion in establishing a diagnosis of myocardial infarction, the presence of the bulge when considered in relation to other clinical information is often significant in confirming or verifying the diagnosis. 4. Part IV. Fifty-one patients with electrocardiographic conduction defects were studied by the kinetocardiographic technique (ultralow — frequency precordial movements). In addition, pertinent clinical data are included. Paradoxical precordial movements (bulges) were noted in 32 of the 51 patients. The records were normal in only 3 of the patients with known heart diseases, whereas the records were normal in 6 of the 10 patients without demonstrable heart disease. Thus, the presence of a bulge in records from patients with electrocardiographic conduction defects is evidence for underlying myocardial disease.