On the basis of principles that are similar to (but differ slightly from) those that underlie M mode and two dimensional techniques, pulsed Doppler echocardiography permits evaluation of intracardiac blood flow noninvasively. This technique is helpful in the diagnosis and management of patients with valvular and congenital heart disease, and in some circumstances provides information not available from M mode or two dimensional imaging. Despite several notable limitations, pulsed Doppler echocardiography is a useful diagnostic technique whose clinical application is likely to increase as future technologic improvements occur.