Between January 1973 and January 1980, 29 patients with biliary atresia treated by Kasai hepatic portoenterostomy were evaluated for deficiencies of vitamin A, D, and E. The mean vitamin A level in 11 patients with successful operations was 25.5 +/- 3.8 (SE) micrograms/100 ml whereas the level was 16.0 +/- 8.8 (SE) micrograms/100 ml in three patients with failed operations (normal: greater than 30 micrograms/100 ml). Vitamin E levels in 6 children (5 with sustained bile drainage) were 2.9 +/- 1.7 (SD) micrograms/ml (normal: greater than 4 micrograms/ml). Vitamin D deficiency was evaluated in 22 patients by serial radiographs of knees and wrists. Four children (18%) had pure osteomalacia and 13 children (59%) had combined osteoporosis and osteomalacia. The four oldest survivors (age 5-5.5 yr) resolved their bone disease without specific treatment. Serologic deficiencies of vitamins A and E and radiographic evidence of vitamin D deficiency exist in patients with biliary atresia despite operative establishment of bile flow. These deficiencies are present in both the younger and the older children. In the case of vitamin D, resolution may occur without specific treatment.