To investigate the characters of the transmitted transmitral A wave associated with a fourth heart sound, left ventricular inflow, and outflow Doppler echocardiography and phonocardiography were recorded in 13 patients with a fourth heart sound and 9 age-matched control subjects. The Doppler echocardiographic data were compared between both groups and the peak velocity and acceleration rate of the transmitted transmitral A wave were correlated with other parameters. The peak velocity and acceleration rate of the transmitted transmitral A wave were significantly greater, but the A wave transit time from the mitral valve to the left ventricular outflow tract (A-Ar interval) was significantly shorter in patients with a fourth heart sound. There was a significant correlation between the A-Ar interval and the peak velocity (r = -0.54, P = 0.01) or acceleration rate (r = -0.63, P = 0.002) of the transmitted transmitral A wave. The A-Ar interval was shown to be the independent determinant of both the peak velocity and acceleration rate of the transmitted transmitral A wave by stepwise multiple linear regression. In conclusion, the presence of a fourth heart sound was associated with a higher peak velocity and acceleration rate of the transmitted transmitral A wave, to which increased ventricular stiffness may make some contributions.