Four cases are presented to illustrate the echo patterns of pulmonary valve motion in patients with pulmonary regurgitation caused by pulmonary hypertension, idiopathic dilatation of the pulmonary artery, or congenital absence of the pulmonary valve or in association with pulmonary stenosis. Absence of the pulmonary 'a' wave, fluttering of the e-f slope, and midsystolic closure or 'notching' of the valve were noted with pulmonary hypertension. In the case with idiopathic dilatation of the pulmonary artery a normal echo pattern of pulmonary valve motion along with distinct dilatation of the pulmonary artery at the valvular level were present. Pronounced dilatation and systolic expansion of the pulmonary artery along with dilatation of the right ventricle were seen with congenital absence of the pulmonary valve. No pulmonary valve could be demonstrated on multiple scans from the right ventricle to pulmonary artery. In Case 4 large 'a' waves (14 mm) were noted, indicating a reversal of the normal end-diastolic gradient across the valve and suggesting that pulmonary regurgitation in this case was associated with right ventricular outflow obstruction. Study of the echo pattern of pulmonary valve motion may therefore provide useful information in establishing the cause of pulmonary regurgitation.