Pulsed Doppler velocimetry of both fetal atrioventricular valves derived in the four-chamber-view were performed in 94 uncomplicated pregnancies between the 20th and the 40th week of gestation. The maximal velocities in early (E-peak) and late diastole (A-Peak) as well as the E/A Ratio were calculated for both tricuspid (TV) and mitral valves (MV). Normal ranges for the six measured parameters were constructed and correlated with gestational age. In the second half of pregnancy an increase of the E-wave for both valves was found (TV r = 0,59; MV r = 0,48) with higher values through the TV compared with the MV. In comparison the A-velocities showed a flat increase during the observation time (TV r = 0,32, MV r = 0,24). The E/A Ratio for both valves which is < 1 in the fetus showed an increase throughout pregnancy, mainly due to the increase of the E-wave in the observed period of time. These intracardiac Doppler flow measurements enable an insight into the physiology of fetal circulation. They give a basis for the analysis of blood flow under pathological conditions, like in congenital heart defects or in intrauterine growth retardation.