Diastolic function of the left ventricle (LV) is principally assessed by analysis of the Doppler velocity flow profiles at the mitral orifice (MO). Assuming the mitral valve is not obstructed, early and late diastolic inflow are influenced not only by the left atrium but also by the LV. We hypothesized that recording of diastolic flow velocity profiles in the mid LV might contribute additional information on the response of the ventricle to filling in diastole. In 58 normal subjects, the differences at the MO and midventricular (MV) levels between the R-E interval (the time in milliseconds from the peak of the R wave of the electrocardiogram to the peak of the early diastolic filling wave), the R-D interval (the time in milliseconds from the peak of the R wave to the beginning of the early diastolic flow wave), and the D-E interval (the time in milliseconds from the onset to the peak of the early diastolic flow wave) were quite small, averaging 13 +/- 17, -21 +/- 27, and -7 +/- 16 ms, respectively (mean +/- SD). At the MO, the E/A velocity ratio averaged 1.6/1, whereas it was significantly greater at the MV level 2.1/1 (p <0.001) due to a relatively greater decrease in the A-wave velocity (37%) compared with the decrease in peak E-wave velocity (18%). The peak A-wave velocity occurred before the R wave (average 44 +/- 19 ms at the MO and 43 +/- 24 ms at the MV level). Abnormal patterns involving both early and late diastole were observed with left ventricular hypertrophy and systolic dysfunction. The method is simple and therefore adaptable for routine clinical practice. Importantly, early diastolic left ventricular function can be assessed in patients in atrial fibrillation as well as sinus rhythm.