Objective: To determine whether tauroursodeoxycholic acid (TUDCA) would prevent or ameliorate the liver injury in neonates treated with total parenteral nutrition (TPN). Study design: Eligible infants were enrolled after surgery when serum direct bilirubin (DB) was <2 mg/dL. TUDCA (30 mg/kg/day) was given enterally to 22 subjects. A concurrent untreated/placebo group was evaluated for comparison (n = 30). Blood chemistries including alanine aminotransferase (ALT), alkaline phosphatase (AP), conjugated bilirubin (CB), and bile acids (BA) were obtained weekly. Results: There was no difference in peak serum CB, ALT, AP, or BA levels between the TUDCA-treated and control infants. When stratified for birth weight (<1500 g and >1500 g), no differences in peak CB, ALT, AP, or BA were noted. Serum CB levels were similar between TUDCA-treated and control infants after 14, 40, 60, 70, and 120 days of TPN. Conclusion: TUDCA appears ineffective in preventing the development or treatment of TPN-associated cholestasis in neonates. Erratic biliary enrichment and prolonged inability to initiate treatment may compromise the utility of enterically administered TUDCA for TPN-treated infants. (J Pediatr 2002;141:237-42)