The hepatic circulation of eight children who underwent Kasai's operation for biliary atresia was serially evaluated by Doppler ultrasonography (US). A total of 36 examinations were performed to evaluate the maximal velocities (mvs) of the main portal vein (MPV), splenic vein (SV), and hepatic artery (HA), and to analyze the spectral waveform and the directions of flow. The mean mvs-MPV in four patients for whom adequate biliary diversion had been achieved and whose serum bilirubin had fallen to within the normal range (group A), was 19.8 +/- 7.5 cm/s. Their MPV waveforms were constant, with blood flowing toward the liver, while their mean mvs-SV was 12.1 +/- 5.8 cm/s. In two other patients with apparent hypersplenism, but whose serum bilirubin levels had fallen to nearly normal (group B), the mean mvs-MPV was 20.7 +/- 10.4 cm/s and the mvs-SV was 22.4 +/- 10.4 cm/s. In contrast, the mvs-MPV in the two remaining patients, whose serum bilirubin levels had either not fallen to within the normal range, or had fallen initially but increased due to recurrent cholangitis (group C), was 14.2 +/- 9.1 cm/s. In these patients, the waveforms were unstable, the MPV flows were occasionally hepatofugal, and their mean mvs-SV was 18.0 +/- 5.8 cm/s. The mvs-HA were markedly increased in the latter four patients, whose clinical condition had also deteriorated. These observations led to the conclusion that hepatic circulation evaluated by serial Doppler US provides important information about liver status in children who have undergone Kasai's operation for biliary atresia.