OBJECTIVE: To test the hypothesis that in very young patients with biliary atresia, cognitive deficits are apparent before transplantation. STUDY DESIGN: With the Mullen Scales of Early Learning (Mullen), we examined 15 infants (mean age, 7.8 months) with biliary atresia, correlating Mullen scores with standard clinical and biochemical parameters. RESULTS: Overall, participants displayed significant delays in gross motor and language skills, and fine motor and visual reasoning skills were relatively preserved. The international normalized ratio correlated inversely with gross (P < .01) and fine (P < .05) motor skills. Growth parameters correlated positively with expressive language ability, but length of hospitalization and mode of feeding did not. Age at performance of the Kasai procedure was found to correlate with receptive language performance (P < .05). CONCLUSIONS: Very young children with biliary atresia display a characteristic profile of early developmental deficits before transplantation. These findings suggest that early intervention and aggressive nutritional management should be the standard of care to minimize neurocognitive effects.