In 25 patients with acute myocardial infarction and in 25 normal subjects, pulsed-wave Doppler echocardiography was performed in the apical four-chamber view with the sample volume first between the mitral leaflet tips and then at the mitral anulus. The early filing wave (E) and late filling wave (A) peak velocities measured from Doppler strip charts were significantly (p less than 0.001) higher at the tips in both groups. E velocity increase was greater than A velocity increase, producing a significantly (p less than 0.001) higher E/A velocity ratio at the tips than at the anulus. The deceleration time was longer at the tips than at the anulus (p less than 0.001) in both groups. Therefore it is important to know sample volume location in the interpretation of mitral inflow velocity. It is critical to maintain the same sample volume location in serial assessments of left ventricular diastolic filling characteristics.