Cardiac function was determined non-invasively in 7 patients (average age 24 years) with chronic uremia. Each was on maintenance hemodialysis. Echocardiograms and carotid pulse tracings were recorded 30 minutes prior to dialysis, and again 30 minutes, 24 and 48 hours following hemodialysis. End-diastolic and end-systolic diameters averaged 5.4 +/- 0.2 and 3.4 +/- 0.1 cm, respectively before and 5.0 +/- 0.2 and 3.2 +/- 0.1 cm immediately after hemodialysis (P less than 0.05 for both). Calculated stroke volume fell from 92.1 +/- 8.8 to 76.7 +/- 10.5 ml (P less than 0.025). Heart rate increased minimally, and average cardiac output was not significantly increased. Following dialysis, body weight and systolic and diastolic blood pressures fell significantly. Thus preload as well as afterload declined. Because of the fall in both stroke volume and end-diastolic volume, a shift along the ventricular function curve downwards and to the left occurred implying diminished cardiac pumping function. Nonetheless the indices of myocardial contractility were normal and showed no change from pre-dialysis value. During the 48 hour interval following hemodialysis all measured and calculated values returned to pre-dialysis levels. Thus organic heart disease as evaluated by non-invasive techniques does not appear to be a necessary sequel to kidney failure, at least in young patients in a hemodialysis program. Gross abnormalities of myocardial function may be absent for at least seven years after the onset of chronic uremia.