BACKGROUND: Liver transplantation in infants younger than 90 days is increasingly common. These infants typically arrive for transplantation in fragile medical condition. It is commonly assumed that they may experience high complication rates, difficult postoperative courses, and poor graft and patient survival. OBJECTIVES: We sought to understand whether graft and patient survival rates in these young infants were lower than in older children, these patients experienced more complications than older children, and health care resource utilization was higher in this population. PATIENTS AND METHODS: Data queried from the Study of Pediatric Liver Transplantation (SPLIT) database were limited to infants ages 0 to 90 days who had received their primary liver transplant between February 1996 and May 2004. Patients older than 90 days registered in the SPLIT database were used for comparison. RESULTS: Thirty-eight patients, ages 0 to 90 days, were included in the analysis. Their severity of illness was reflected by a median calculated Pediatric Endstage Liver Disease score of 34.8 at transplant. A majority (89.5%) of infants received cadaveric liver grafts, of which 47% were reduced organs. The infants experienced prolonged hospitalizations, spending an average of 50.9 +/- 7.6 days in the hospital after transplant. Long stays in the intensive care unit (average 22.1 +/- 1.5 days) and need for mechanical ventilation (average 16.2 +/- 2.7 days) also occurred. Length of hospitalization, intensive care, and mechanical ventilation were significantly higher than in older children (P < 0.0001). The reoperation rate (60.5%) was high and significantly greater than in older children (P = 0.007), with 10 patients (26.3%) needing 3 or more early reoperations. Reoperations occurred for bleeding, wound complications, biliary complications, and sepsis. There was no difference in vascular or biliary tract complications compared with older children. Bacterial infections were also common (52.6%) and were seen with greater frequency than in older children (P < 0.04). This infant cohort had an overall graft survival of 76.1% and overall patient survival of 87.8% at 1 year, with median follow-up of 12.5 months (range 0.6-84.0 months). Graft and patient survival in infants younger than 90 days was similar to that in older infants and children (P = NS). CONCLUSIONS: Young infants experience graft and patient survival similar to that in older cohorts of liver transplant recipients. Posttransplant complication rates, including the reoperation rate, were higher in this younger group, and the duration of hospitalization and intensive support were significantly longer. Future studies to better examine the factors, including age, that may contribute to the need for reoperation in children are warranted. Recognition and further analysis of the cost of care in this age group is also needed.