Options for atrioventricular (AV) valve replacement in small pediatric patients are very limited. The Melody valve has shown reasonable short-term outcomes. This study was aimed at identifying predictors of valve failure following AV valve replacement with a Melody valve at a single-center. 26 patients underwent 37 AV valve replacements with 31/37 (84%) of valves placed in the systemic AV valve position. Median age at procedure was 17months (IQR 4-33) and weight was 8.5kg (IQR 6.25-12.85). Median balloon size for valve implant was 20mm (IQR 18-22). Repeat intervention occurred in 21 cases (57%) with repeat surgery in all but one. Median freedom from re-intervention was 31months; 19% were free from re-intervention at 60months. Age < 12months weight < 10kg and BSA < 0.4 m2 were all significant risk factors for early valve failure (p = 0.003, p 0.017, p 0.025, respectively). Valve longevity was greatest with balloon inflation to diameter 1.20-1.35 times the patient's expected annular diameter (Z0), relative to both smaller or larger balloons (p = 0.038). In patients less than 12months of age, patients with single ventricle physiology had an increased risk of early valve failure (p = 0.004).