We measured intellectual and motor function, social competence, and growth in 29 children (mean age 4 years 7 months) before liver transplantation and 1 year later. We used either the Bayley Scales, the Stanford-Binet Intelligence Scale, and the Minnesota Child Development Inventory (MCDI), Motor Age Quotient, or the Wechsler Scales, depending on the age of the child at testing. Social function was measured with the MCDI or the Child Behavior Checklist. All anthropometric measures were expressed relative to normal values for age and sex. Patients whose intellectual and motor scores were less than 80 before transplantation gained an average of 8 points, but these changes were not statistically significant, nor were the changes on these measures for the group as a whole. The development of children with onset of liver disease in the first year of life was more likely to remain delayed after transplantation. Older subjects improved significantly in social competence (p less than 0.008). There were significant increments after transplantation in weight, head circumference, and arm anthropometrics (p less than 0.0001 to 0.04), but there was no change in linear growth rate. Increments in length correlated negatively with steroid dosage, and change in head circumference was associated with age at time of transplantation (p less than 0.005 to 0.10).