Doppler echocardiographic measurement of transmitral filling velocities seems to be a sensitive marker for resting left ventricular diastolic abnormalities in patients with coronary artery disease. The behaviour of these filling velocities during induced myocardial ischaemia, however, has not been fully studied. Left ventricular filling was assessed by pulsed Doppler ultrasound in 21 patients with angina pectoris and coronary artery disease and in five controls (patients with chest pain but without myocardial ischaemia). High dose dipyridamole infusion (0.9 mg/kg over 10 minutes) was used to provoke myocardial ischaemia, which was assessed by symptoms and electrocardiographic ST segment change. Doppler indices of diastolic filling were measured and the results expressed as percentage change from baseline values. Dipyridamole increased the heart rate and reduced systolic blood pressure equally in both groups. In the controls dipyridamole increased the peak filling velocities of both the early and atrial filling waves. In the 12 patients with coronary artery disease who did not develop evidence of myocardial ischaemia, the effect on left ventricular filling velocity resembled that in the controls though the time to peak change was delayed. Six of the nine patients with dipyridamole induced myocardial ischaemia had a significantly reduced maximum changes in early (+30% v +18%) and atrial (-0.2% v +33%) filling velocities compared with the controls. The remaining three patients had a decrease in early filling velocity (-20%) with an associated increase in atrial peak filling velocity (+21%). Dipyridamole increased diastolic filling velocities in the controls. In patients with coronary artery disease there was a variable change in diastolic filling indices which may be attributed either to the degree of myocardial ischaemia or to the different haemodynamic changes occurring during myocardial ischaemia.