Differentiation between intra and extra hepatic causes of neonatal cholestasis can be difficult. Combination of routine hepatobiliary scintigraphy (HBS) after priming with choleretic therapy and closed liver biopsy is 100% effective in confirming the diagnosis. (Tolia, et al. J.Ped.GI and Nutr. 5:30, 1986). In an attempt to improve the accuracy of HBS, similtaneous measurement of the time activity curve (TAC) on the duodenal aspirate(DA) was performed in 9 patients. TAC on DA ranged widely from 151-986,000 cpm/100 ul per mCi dose and was non discriminatory. This may have been secondary to contamination of DA by free 99mTc secreted into the stomach as breakdown of Disofenin® occurs releasing free pertechnetate. A further 24 patients were studied with simultaneous gastric aspirate (GA) and DA. If imaging for gut activity alone is used, extra hepatic biliary atresia (EHBA) was diagnosed in 11/24. Using DA corrected for GA with a cut off point of 1500 cpm/100 ul per mCi dose, then EHBA was diagnosed in 4/24 with two false positives. There was one false negative for EHBA with the DA count being 2741 cpm/100 ul/mCi dose. These data suggest that although additional DA and GA TAC improve the specificity for routine HBS, liver biopsy should still be considered if the cholestasis is not improved within 6 weeks of age.