Abstract: In this prospective study, 49 infants with prolonged jaundice, were studied between January 2005 to April 2007 in Tabriz Children`s Hospital. All of these infants were evaluated with ultrasonography and isotopscan and finally biopsy was done in all of them under guide of sonography. In their sonographic evaluation, absence or presence of gall bladder, its size and also its evacuation after feeding was checked and beside this triangular cord sign was controlled. The PPV and specificity of triangular cord sign in diagnosis of extrahepatic biliary atresia (EHBA) was 100% but its NPV was only 78.5%. The overall accuracy, PPV, NPV, specificity and sensitivity of ultrasonographic findings in diagnosis of EHBA was about 94, 92, 94, 97 and 86%. Ultrasonography is a reliable screening method in early diagnosis of EHBA and triangular cord sign increases its accuracy especially its specificity.