The purpose of this study was to quantify and determine predictors of long-term survival and functional outcome in patients with double-inlet left ventricle (DILV) after the Fontan operation. The Fontan operation has become the procedure of choice for DILV. Early survival has improved, but mortality and morbidity persist. Record review and follow-up questionnaires were used to ascertain the status of 225 patients with DILV who had Fontan operations from 1974 to 2001 at the Mayo Clinic. The median age at operation was 9 years. The median follow-up period was 12 years (range 3 months to 25 years). There were 22 deaths (9.3%) <30 days after the operation. Early mortality decreased to 3% (2 of 70 patients) after 1989. Overall late survival was 78% (159 of 203 patients). Actuarial survival for the 203 early operative survivors at 5, 10, 15, and 20 years was 91%, 80%, 73%, and 69%, respectively. Forty-nine percent (99 of 203) had additional surgical procedures after the Fontan operation. Other frequent late events were atrial flutter or fibrillation (57%), protein-losing enteropathy (9%), and thromboembolic events (6%). Current health status was described as good or excellent by 84% of patients, fair by 18%, and poor by 12%. In conclusion, the Fontan operation for DILV is now performed with a low operative mortality rate. Long-term survival has improved, and most patients have good functional status.