The advancements in Doppler methodology in the past decade have dramatically changed the way we assess children with heart disease. Techniques to determine pressures, gradients, shunt flows, and regurgitant lesions have shifted the noninvasive studies into areas that were strictly the venue of catheterization a decade ago. The more recent color Doppler developments take the 2DE image one step further by providing some of the flow visualization previously available only through angiography. When applied to appropriate clinical settings Doppler methodology will continue to provide us with increasingly sophisticated and precise definitions of intracardiac physiology.