Left ventricular end-diastolic pressure (LVEDP) measured at cardiac catheterisation and simultaneous mitral flow patterns obtained by pulsed Doppler ultrasound scanning were assessed in twenty patients (fourteen males) with ischaemic heart disease. The ratio of passive and active components of mitral flow showed a significant linear correlation with LVEDP. Active (left atrial) mitral flow diminished as left ventricular end-diastolic pressures increased. Mitral flow ratios greater than 2 were always associated with LVEDP greater than 20 mmHg. This application of Doppler echocardiography provides a simple non-invasive method of estimating LVEDP.