We used the discharge database of the University Hospital Consortium to determine the management and early outcome of neonates with hypoplastic left heart syndrome admitted to member institutions from 1990 to 1999. Of the 2,264 patients, 1,203 underwent a Norwood procedure, with 42% mortality. Cardiac transplantation was performed in 72, with 38% mortality, and 217 (10%) were discharged without any surgical procedure. The proportion of patients managed by the Norwood procedure increased from 43% during the first half of the decade to 59% in the second half, with corresponding decreases in the proportion managed by transplantation or nonintervention. A mortality rate of < or =40% was achieved in all 5 institutions performing >50 Norwood procedures, and by 9 of 40 institutions performing <50. Performance of a Norwood procedure has become the most frequent management for neonates with hypoplastic left heart syndrome. Lower operative mortality rates are generally, but not exclusively, achieved by institutions with high surgical volume.