This paper reports our 9-year experience treating 34 infants with biliary atresia utilizing a new non-invasive diagnostic method, ultrasonographic "triangular cord"(TC) sign. The TC sign is present when there is visualization of a triangular or a band-like echogenicity just cranial to the portal vein. The ultrasonographic TC sign appears to be a simple, non-invasive, time-saving and useful tool in the diagnosis of biliary atresia. Sensitivity is 84 %. Active bile excretion was restored in 90 % of the patients who were treated between 31-60days, 78 % of those between 61-90 days, and 33 % of those being 91days or older. The incidence of postoperative cholangitis was 36 %. Construction of an antireflux valve in the Roux-en-Y loop did not affect the incidence of postoperative cholangitis(p=0.18). Among 34 infants with biliary atresia, 23(68 %) are alive for 2-102 months after operation, and 12 are alive for more than 5 years. Five-year estimate survival by Kaplan-Meier method was 66 %.