Since the introduction of duplex Doppler sonography the noninvasive assessment of hemodynamic changes in children has become possible. The clinical application comprises the depiction of cerebral hemodynamics in infants, where characteristic flow patterns can be found in patent ductus arteriosus, hypoxic-ischemic encephalopathy, cerebral hemorrhage, hydrocephalus or in brain death. Moreover, Duplex Doppler Sonography play an important role in the evaluation of renal hemodynamics, especially in kidney transplants. Finally, the examination of the portal venous system can demonstrate thrombosis of the portal vein, portosystemic collaterals or a hepatofugal flow in severe portal hypertension. Thus, invasive investigative procedures may become unnecessary in certain cases. The future potential of this technique lies in the development of quantitative measurements of volume flow and in Doppler color flow imaging.