The optimal approach to hypoplastic left heart syndrome (HLHS) is controversial. The palliative Norwood operation, cardiac transplantation, and no surgical intervention have all been advocated. Centers that perform the Norwood operation have met with varied results, and conflicting reports exist regarding factors predictive of stage I outcome. From January 1990 to January 1996, 67 patients with HLHS were admitted with intent to perform the staged Norwood procedure. Fourteen patients did not undergo surgery. In the 53 patients treated surgically, outcome was reviewed, and 10 potential risk factors for first stage mortality were analyzed. Forty-one infants survived the Norwood I operation to hospital discharge (77% of the surgically treated patients and 61% of the entire group, including those who did not undergo operation) with 6 additional deaths 3 to 5 months after operation. Univariate analysis showed cardiopulmonary bypass time and circulatory arrest time to be significant risk factors for hospital mortality. Multivariate analysis revealed only cardiopulmonary bypass time as significant (p <0.01). Of the 15 prenatally diagnosed newborns who underwent surgery, 11 survived (p = 0.72). Ten of 11 patients with preoperative organ damage survived (p = 0.42). Among the 35 bidirectional Glenn (Norwood II) and Fontan (Norwood III) procedures performed, there were 2 deaths. The 5-year actuarial survival for patients who underwent operations was 61%. The Norwood procedure is a favorable option for the infant with HLHS. Surgical survival may be affected by a prolonged cardiopulmonary bypass time, but is not affected by other factors analyzed, including prenatal diagnosis and preoperative organ damage.