Patent ductus arteriosus may occur as an isolated lesion or in association with congenital cardiac malformations. Echocardiography in conjunction with colour Doppler displays the morphology of the ductus and its anatomic variations. Analysis of ductal flow by pulsed wave Doppler provides valuable haemodynamic information in neonates allowing to distinguish right to left, bidirectional and left to right shunting. In older children, continuous wave Doppler provides the possibility for noninvasive determination of systolic pulmonary artery pressure by calculation of the pressure gradient across the duct. In patients with complex congenital heart disease, who are dependent on patency of the ductus in the neonatal period, Doppler echocardiography is essential to monitor treatment with prostaglandin E1. Following interventional or surgical closure, colour Doppler is the method of choice to verify the result and to confirm complete closure of the ductus.