The effects of acute blood volume reduction induced by haemodialysis on diastolic time intervals were studied in 19 patients by echo- and phonocardiography. Haemodialysis significantly decreased left ventricular diameters. The isovolumic relaxation time was prolonged and negatively correlated with left ventricular end diastolic dimensions. To study the effect of load reduction on left ventricular filling time, cardiac cycles with the same R-R interval, before and after haemodialysis, were compared. At any given R-R interval dialysis resulted in a significant prolongation of the filling time. This study shows that diastolic time intervals are dependent on left ventricular loading conditions, and this effect should be considered when these time intervals are evaluated in the clinical setting.