Evaluation of long-term results after the Ross/Ross–Konno operation in patients <18 months of age, focusing on pulmonary autograft performance. Retrospective analysis of patients who underwent the Ross/Ross–Konno operation (1991–2011). Data were obtained from hospital records and follow-up was 100% complete. Between January 1991 and December 2011, 140 patients underwent the Ross/Ross–Konno operation and 22 patients were <18 months of age (male/female: 15/7). The median age was 166 days. 14 patients had a Ross operation and 8 patients a Ross–Konno operation. Presentation at surgery was aortic valve stenosis in 13, regurgitation in 7 and mixed disease in 2. Only 4 patients (18%) had no surgery prior to Ross/Ross–Konno, and among the others the previous most frequent operation was aortic valvotomy (55%). There were 3 early deaths, all in high-risk cases with poor preoperative left ventricular function. At discharge there was no neoaortic regurgitation in 10, trivial in 4 and mild in 5. The median follow-up is 10.8 years (range 0.96–21). There was 1 late death due to progressive ventricular dysfunction 2.4 years after Ross–Konno and mitral valve replacement. Survival for patients <18 months was 81% at 5–10 years (18 patients) and for older patients was 98.2% at 5–10 years. There was no neoaortic regurgitation in 8 patients, mild in another 8 and moderate in 2 with a freedom from moderate regurgitation significantly lower in comparison with older patients (100–80% vs 83.5–73.4% at 5–10 years). Freedom from aortic reoperation for patients <18 months was significantly higher compared with older (100 vs 95.4–84.4% at 5–10 years, P < 0.04). Reoperation in the RVOT was higher in younger patients compared with the other (85–64.6% vs 97.2 and 84.7% at 5–10 years P = 0.02). Z-score aortic root diameter remained constant in the 18-months patients (P < 0.01). Ross/Ross–Konno can be invaluable in the younger age group but not without risk in the setting of ventricular dysfunction. Long-term performance of the neoaortic valve is significantly better than in older children, which is related to maintenance of normal root dimensions compared with progressive dilatation in patients undergoing Ross/Ross–Konno at older ages.