The objective of this study was to undertake a pilot assessment of zinc status in infants and children with extrahepatic biliary atresia. Plasma zinc concentrations and urine zinc excretion rates were measured longitudinally in 45 infants and young children with this disorder. The mean (+/- SD) plasma zinc (298 observations) was 56.8 +/- 17.9 micrograms/dl (controls 85.6 +/- 10.8). Plasma zinc was not correlated with age and did not appear to be related to repeated surgical procedures or to episodes of cholangitis. Plasma zinc was only weakly correlated with serum albumin (r = 0.27, p less than 0.001). The 24-h urine zinc excretion rates were correlated with age but not so strongly as for normal children. Hyperzincuria was evident from the linear regression equation of 24-h urine zinc on age. On a body weight basis, urine zinc excretion rates were approximately 6 times normal for the first 2 years and remained high across the entire age range. To replace these losses, net zinc absorption would need to increase by 40%. The relationship of these data to the zinc nutritional status of these patients and to their underlying hepatic disease remains to be clarified by more definitive studies.