Our aim was to evaluate whether early timing of total cavopulmonary connection (TCPC) affects postoperative outcomes.Of 460 consecutive TCPC patients, 51 (11.1%) underwent TCPC <= 18 months of age (group A), and 409 patients >18 months of age (group B). We compared the clinical outcomes and exercise capacity between groups.Median age at TCPC was 1.4 (interquartile ranges: 1.3-1.5) years in group A and 2.5 (1.9-4.5) years in group B. Duration of intensive care unit stay (6 vs 7 days), hospital stay (20 vs 20 days), and 30-day survival (100 vs 98%) was not significantly different between groups. Estimated survival (95.3 vs 92.1%), freedom from reoperation (93.7 vs 86.3%), freedom from catheter intervention (60.1 vs 77.0%), and freedom from protein losing enteropathy (97.6 vs 93.8%) at 10 years was not significantly different between groups. At last follow-up, no patient in group A but 13 patients in group B exhibited reduced ventricular function ( P = 0.035). Exercise-capacity testing showed that both peak oxygen uptake (36.4 vs 28.6 ml/kg/min; P = 0.026) and its percentage of predicted value (82.9 vs 70.0%; P = 0.004) were significantly higher in group A ( n = 6, mean postoperative period: 8.9 years) than in group B ( n = 119, mean postoperative period: 8.7 years).Fontan completion for TCPC can be performed at an early age with a low perioperative risk and good intermediate results. Earlier unloading of the systemic ventricle and earlier elimination of chronic cyanosis by staged cavopulmonary connection might be advantageous for preservation of long-term ventricular function.